Touch panel system and electronic device

ABSTRACT

A touch sensor panel disclosed herein includes: a plurality of vertical electrodes ( 6 ); and a plurality of horizontal electrodes ( 7 ), the plurality of vertical electrodes ( 6 ) and the plurality of horizontal electrodes ( 7 ) (i) being so disposed that, as viewed in the direction perpendicular to a substrate, the plurality of vertical electrodes ( 6 ) include no segment coincident with the plurality of horizontal electrodes ( 7 ) and (ii) forming a uniform grid having no gap.

TECHNICAL FIELD

The present invention relates to a touch panel system and an electronicdevice including the touch panel system. Particularly, the presentinvention relates to a touch panel system and an electronic device eachof which (i) includes: a plurality of vertical electrodes provided on avertical electrode surface and arranged at predetermined intervals in ahorizontal direction; a plurality of horizontal electrodes provided on ahorizontal electrode surface, which is parallel to the verticalelectrode surface, and arranged at predetermined intervals in a verticaldirection; and an insulator provided between the vertical electrodesurface and the horizontal electrode surface to insulate the verticalelectrodes from the horizontal electrodes and (ii) is capable ofreliably and effectively removing (canceling) a noise generated by adisplay device, etc.

BACKGROUND ART

Recently, introduction of touch panel systems to various kinds ofelectronic devices has been growing rapidly. For example, the touchpanel systems are introduced to portable information devices such assmartphones and automatic vending machines such as automatic ticketmachines.

The touch panel system is typically configured to include (i) a displaydevice and (ii) a touch panel stacked on an upper side (front surface)of the display device. Therefore, a sensor provided on the touch panelis likely to be affected not only by a noise such as a clock generatedin the display device but also by other noises coming from the outside.Such the noises lead to impairment in detection sensitivity for a touchoperation.

Patent Literature 1 describes a touch panel system (coordinates inputdevice) including a countermeasure against such noises. The touch panelsystem of Patent Literature 1 includes a noise processing section forremoving a noise. FIG. 19 is a block diagram illustrating a noiseprocessing section 100 included in the touch panel system of PatentLiterature 1. As shown in FIG. 19, the noise processing section 100includes a filter section 101, a logical inversion section 102, and anadding section 103. The filter section 101 receives an output signal(analog signal) from a sensor provided in a touch panel (notillustrated). The filter section 101 extracts, as a noise signal, an ACsignal component included in the input signal. The logical inversionsection 102 inverts by 180° the phase of the noise signal thusextracted. The adding section 103 adds, to the input signal which issupplied to the filter section 101 and which includes the noise signal,the noise signal whose phase has been inverted by 180°.

Thus, according to the touch panel system of Patent Literature 1, thenoise signal extracted by the filter section 101 is inverted, and thesignal thus inverted is added to the input signal (analog signal)supplied from the sensor. Namely, to the noise component included in theinput signal supplied from the sensor, such a signal is added which hasthe same level as the noise component and whose phase has been inverted.This cancels the noise superimposed on the input signal supplied fromthe sensor. This makes it possible to reduce effects given by the noiseincluded in the input signal supplied from the sensor.

On the other hand, the description below deals with an arrangement ofvertical electrodes and horizontal electrodes in a conventionalcapacitive touch sensor panel. FIG. 55 is a diagram illustrating anarrangement of vertical electrodes 91 and horizontal electrodes 92 in aconventional capacitive touch sensor panel. FIG. 55 corresponds to FIG.3 of Patent Literature 2.

This conventional capacitive touch sensor panel disclosed in PatentLiterature 2 includes (i) a plurality of vertical electrodes 91 providedon a vertical electrode surface and arranged at predetermined intervalsin a horizontal direction and (ii) a plurality of horizontal electrodes92 provided on a horizontal electrode surface, which is parallel to thevertical electrode surface, and arranged at predetermined intervals in avertical direction.

Each vertical electrode 91 includes a sequence of a repeat ofdiamond-shaped quadrangular sections 93 and 94 connected to each otherin the vertical direction. Each horizontal electrode 92 includes asequence of a repeat of diamond-shaped quadrangular sections 95 and 96connected to each other in the horizontal direction.

The vertical electrodes 91 and the horizontal electrodes 92, eachincluding diamond-shaped sections, are so provided that the verticalelectrodes 91 cross the horizontal electrodes 92 to constitute acapacitive touch sensor panel. In the case where such a capacitive touchsensor panel is to be placed on a display device for use, the verticalelectrodes 91 and the horizontal electrodes 92 are normally each formedof transparent conductive film made of, for example, ITO (indium tinoxide). Recent years have also witnessed research on the use of grapheneas a substitute for ITO.

In the case where the diamond-shaped sections as illustrated in FIG. 55are made of, for example, ITO and arranged on a plane, eachdiamond-shaped section, having both center-line symmetry andcenter-point symmetry, exhibits a similarly symmetric capacitance changewhen touched by an object, such as a pen, that has a small touch area.Utilizing this symmetry in a capacitance change allows a symmetricposition correction to be carried out during a touch-position detection,and thus increases the position detection precision.

FIG. 56 is a diagram illustrating an arrangement of vertical electrodes81 and horizontal electrodes 82 in another conventional capacitive touchsensor panel, which is disclosed in Patent Literature 3. Both thevertical electrodes 81 and the horizontal electrodes 82 are arranged atpredetermined intervals. The vertical electrodes 81 extend in adirection orthogonal to the direction in which the horizontal electrodes82 extend. The vertical electrodes 81 and the horizontal electrodes 82are arranged in the shape of a grid. The vertical electrodes 81 andhorizontal electrodes 82 themselves individually include fine wires,which form a mesh.

(a) of FIG. 57 is a diagram illustrating an arrangement of verticalelectrodes 71 in yet another conventional capacitive touch sensor panel,which is disclosed in Patent Literature 4. (b) of FIG. 57 is a diagramillustrating an arrangement of horizontal electrodes 72 in thatcapacitive touch sensor panel.

(a) of FIG. 57 illustrates an array of vertical electrodes 71 eachincluding sections that each have a shape similar to a diamond shape andthat are connected to one another in a vertical direction. (b) of FIG.57 similarly illustrates an array of horizontal electrodes 72 eachincluding sections that each have a shape similar to a diamond shape andthat are connected to one another in a horizontal direction.

(a) of FIG. 59 is a diagram illustrating an arrangement of verticalelectrodes in still another conventional capacitive touch sensor panel,which is disclosed in Patent Literature 5. (b) of FIG. 59 is a diagramillustrating an arrangement of horizontal electrodes in that capacitivetouch sensor panel.

The capacitive touch sensor panel disclosed in Patent Literature 5 is acapacitance-type touch panel switch including (i) an electricallyconductive X pattern group 161 including a plurality of conductive Xsequences 162 arranged at slight intervals in the X direction and (ii)an electrically conductive Y pattern group 166 including a plurality ofconductive Y sequences 167 arranged at slight intervals in the Ydirection.

Each conductive X sequence 162 includes (i) a plurality of conductive Xpads 163 that each have a substantially rhombic outline and that arearranged in the Y-axis direction and (ii) conductive X pads 163 a thateach have a substantially isosceles-triangular outline and that arearranged in the Y-axis direction to sandwich the conductive X pads 163.Adjacent conductive X pads 163 and 163 are connected to each other by aconductive X line 164, while adjacent conductive X pads 163 and 163 aare also connected to each other by a conductive X line 164.

The conductive X pads 163 and 163 a each include a mesh of (i) finewires extending in the X direction and (ii) fine wires extending in theY direction. Each conductive X line 164 is thin and includes threestraight lines 165 extending in the Y direction and arranged atpredetermined intervals in the X direction.

Each conductive Y sequence 167 includes (i) a plurality of conductive Ypads 168 that each have a substantially rhombic outline and that arearranged in the X-axis direction and (ii) conductive Y pads 168 a thateach have a substantially isosceles-triangular outline and that arearranged in the X-axis direction to sandwich the conductive Y pads 168.Adjacent conductive Y pads 168 and 168 are connected to each other by aconductive Y line 169, while adjacent conductive Y pads 168 and 168 aare also connected to each other by a conductive Y line 169.

The conductive Y pads 168 and 168 a each include a mesh of (i) finewires extending in the X direction and (ii) fine wires extending in theY direction. Each conductive Y line 169 is thin and includes threestraight lines 160 extending in the X direction and arranged atpredetermined intervals in the Y direction.

The X pattern group 161 and Y pattern group 166 arranged as above are soplaced on top of each other as to extend orthogonally to each other in aplaner view. The conductive X lines 164 of the conductive X sequences162 and the conductive Y lines 169 of the conductive Y sequences 167 arestacked on top of each other to form a light-transmitting region havinga light-transmitting property substantially identical to that of theconductive X pads 163 and the conductive Y pads 168.

CITATION LIST Patent Literature 1

Patent Literature

-   Japanese Patent Application Publication, Tokukai, No. 2001-125744 A    (Publication Date: May 11, 2001)    Patent Literature 2-   U.S. Pat. No. 4,639,720, specification (Jan. 27, 1987)    Patent Literature 3-   Japanese Patent Application Publication, Tokukai, No. 2011-113149 A    (Publication Date: Jun. 9, 2011)    Patent Literature 4-   Japanese Patent Application Publication, Tokukai, No. 2010-39537 A    (Publication Date: Feb. 18, 2010)    Patent Literature 5-   Japanese Patent Application Publication, Tokukai, No. 2011-175412 A    (Publication Date: Sep. 8, 2011)

SUMMARY OF INVENTION Technical Problem

However, the touch panel system of Patent Literature 1 has a problem ofbeing incapable of removing noises other than an AC signal component.

Specifically, as described above, with respect to an input signalsupplied from the sensor, the touch panel system of Patent Literature 1regards as a noise an AC signal component included in the input signal.The filter section 101 extracts the AC signal, and thereafter thelogical inversion section 102 inverts the phase of the AC signal by180°. Further, the adding section 103 adds the inverted signal to theinput signal which includes the AC signal component. Thus, for the noiseprocessing according to Patent Literature 1, the process performed bythe filter section 101 for extracting the AC signal component is themost important.

However, Patent Literature 1 fails to disclose details of theconfiguration of the filter section 101. Therefore, it is unknown howmuch noise the touch panel system of Patent Literature 1 can remove.Furthermore, Patent Literature 1 regards as a noise an AC signalcomponent included in an analog signal. Namely, the touch panel systemof Patent Literature 1 basically assumes removal of an impulse noiseonly, and does not assume, as the subject of removal, noises other thanthe impulse noise. Therefore, the touch panel system of PatentLiterature 1 cannot reliably cancel a wide variety of noises other thanthe impulse noise.

The arrangement illustrated in FIG. 55, however, is problematic in thatITO and graphene each have too high a resistance value to produce alarge capacitive touch sensor panel having a size of 30 inches orlarger. The above arrangement thus involves a method for makingdiamond-shaped sections from fine lines of a metal (for example, Ag orCu) that has a low resistance value (Patent Literature 3 [FIG. 56] andPatent Literature 4 [FIG. 57]).

The arrangement illustrated in FIG. 56 problematically includescross-shaped openings 97 that are present at certain intervals and thatare not covered by the grid. The openings 97 are thus visuallyrecognized, with the result of moire occurring. The above arrangementfurther has a problem of a decrease in position detection precisionwhich decrease is due to the fact that the capacitance for the openings97 is changed by a touch differently from that for the other region.

FIG. 58 is a diagram illustrating a uniform grid 73 constituted by thevertical electrodes 71 and the horizontal electrodes 72. The arrangementillustrated in FIG. 57, although free from openings such as thoseillustrated in FIG. 56, includes vertical electrodes 71 and horizontalelectrodes 72 none of which has center-line symmetry or center-pointsymmetry. Further, placing the vertical electrodes 71 and the horizontalelectrodes 72 on top of each other results in zigzag shapes 78 and 79being formed respectively along the left side and bottom side of thegrid 73 as illustrated in FIG. 58. This problematically makes itdifficult to easily join, directly to the grid 73, (i) an address linefor driving the horizontal electrodes 72 (or the vertical electrodes 71)and (ii) an address line for reading a signal from the verticalelectrodes 71 (or the horizontal electrodes 72).

The arrangement illustrated in FIG. 59 includes (i) conductive X lines164 that are parallel to the Y axis and (ii) conductive Y lines 169 thatare parallel to the X axis. A conductive X line 164 is stacked on aconductive Y line 169 to form a light-transmitting region, which thusincludes (i) straight lines parallel to the Y axis and (ii) straightlines parallel to the X axis. Thus, placing this capacitive touch sensorpanel on, for example, a liquid crystal display problematically allowsmoire to occur.

The present invention was made in view of the foregoing problems of theconventional technique, and an object of the present invention is toprovide a touch panel system and an electronic device each of which iscapable of reliably removing a wide variety of noises.

It is another object of the present invention to provide a touch panelsystem and an electronic device each of which includes a uniform gridwith no visible gap and that can prevent moire or the like when placedon a display device.

Solution to Problem

In order to attain the foregoing objects, a touch panel system of thepresent invention includes: a touch panel; and a touch panel controllerfor processing a signal supplied from the touch panel, the touch panelincluding (i) a main sensor section for detecting a touch operationperformed with respect to the touch panel and (ii) a sub sensor sectionprovided in a surface of the touch panel in which surface the mainsensor section is provided, the touch panel controller including asubtracting section for (i) receiving a signal supplied from the mainsensor section and a signal supplied from the sub sensor section and(ii) subtracting, from the signal supplied from the main sensor section,the signal supplied from the sub sensor section, the main sensor sectionbeing provided with a plurality of sense lines, the sub sensor sectionbeing provided with a sub sense line extending along a direction inwhich the sense lines extend, the subtracting section finding a firstdifference which is expressed by (Sn+1)−Sn, the first differencecorresponding to a difference between (i) a signal of a sense line Snwhich is selected from the plurality of sense lines and (ii) a signal ofa sense line Sn+1, which is one of two sense lines adjacent to the senseline Sn, the two sense lines being the sense line Sn+1 and a sense lineSn−1 each of which is included in the plurality of sense lines, thesubtracting section finding a second difference which is expressed bySn−(Sn−1), the second difference corresponding to a difference between(i) the signal of the sense line Sn and (ii) a signal of the sense lineSn−1, which is the other one of the two sense lines, the subtractingsection finding a third difference, the third difference correspondingto a difference between (i) a signal of the sub sense line and (ii) asignal of a sense line adjacent to the sub sense line which sense lineis included in the plurality of sense lines, the touch panel controllerincluding an adding section for adding up the first difference, thesecond difference, and the third difference, the touch panel furtherincluding: a plurality of vertical electrodes (i) each including arepeat of first basic shapes connected to one another in a verticaldirection, the first basic shapes each including a fine wire, (ii)provided on a vertical electrode surface, and (iii) arranged at apredetermined interval in a horizontal direction; a plurality ofhorizontal electrodes (i) each including a repeat of second basic shapesconnected to one another in the horizontal direction, the second basicshapes each including a fine wire, (ii) provided on a horizontalelectrode surface parallel to the vertical electrode surface, and (iii)arranged at a predetermined interval in the vertical direction; and aninsulator provided between the vertical electrode surface and thehorizontal electrode surface so as to insulate the plurality of verticalelectrodes and the plurality of horizontal electrodes from each other,the plurality of vertical electrodes and the plurality of horizontalelectrodes (i) being disposed so that, as viewed in a directionperpendicular to the vertical electrode surface, the plurality ofvertical electrodes include no segment coincident with the plurality ofhorizontal electrodes and (ii) forming a uniform grid having no gap.

According to the above configuration, the main sensor section and thesub sensor section are provided in (on) the same surface of the touchpanel. This allows both of (i) an output signal supplied from the mainsensor section and (ii) an output signal supplied from the sub sensorsection to include various kinds of noise signals reflected in the touchpanel. Furthermore, the subtracting section finds a difference between(i) the output signal supplied from the main sensor section which signalincludes a signal derived from the touch operation and the noise signalsand (ii) the output signal supplied from the sub sensor section whichsignal includes the noise signals. This removes the noise componentsfrom the output signal supplied from the main sensor section, therebyextracting the signal derived from the touch operation itself. Thismakes it possible to reliably remove (cancel) a wide variety of noisesreflected in the touch panel.

Further, according to the above configuration, the subtracting sectionobtains a difference signal value between sense lines adjacent to eachother. Namely, a difference is found between the adjacent sense lines,which have a higher correlation in terms of noise. Furthermore, from anoutput signal supplied from each sense line, a signal (noise signal) ofthe sub sense line is removed. This makes it possible to remove a noisemore reliably.

Furthermore, the above arrangement disposes (I) a plurality of verticalelectrodes (i) each including a repeat of first basic shapes connectedto one another in a vertical direction, the first basic shapes eachincluding a fine wire, (ii) provided on a vertical electrode surface,and (iii) arranged at a predetermined interval in a horizontal directionand (II) a plurality of horizontal electrodes (i) each including arepeat of second basic shapes connected to one another in the horizontaldirection, the second basic shapes each including a fine wire, (ii)provided on a horizontal electrode surface parallel to the verticalelectrode surface, and (iii) arranged at a predetermined interval in thevertical direction so that (i) as viewed in a direction perpendicular tothe vertical electrode surface, the plurality of vertical electrodesinclude no segment coincident with the plurality of horizontalelectrodes and that (ii) the plurality of vertical electrodes and theplurality of horizontal electrodes form a uniform grid having no gap.Thus, preparing an electrode distribution with (i) the verticalelectrodes, (ii) the horizontal electrodes, and (iii) an insulating filmsandwiched therebetween forms a uniform grid having no visible gap. Suchan electrode distribution, as placed on a display device, can preventmoire and the like from occurring.

In order to attain the foregoing objects, another touch panel system ofthe present invention includes: a touch panel; and a touch panelcontroller for processing a signal supplied from the touch panel, thetouch panel including a sensor section, the sensor section beingprovided with a plurality of sense lines and detecting a touch operationperformed with respect to the touch panel, the touch panel controllerincluding a subtracting section for (i) receiving signals from thesensor section and (ii) finding differences in signal between, among thesense lines, respective pairs of sense lines adjacent to each other, thetouch panel system further including: drive lines provided so as tointersect the sense lines; a drive line driving circuit for driving thedrive lines in parallel; and capacitances being formed between the senselines and the drive lines, the subtracting section receiving outputsignals from the sense lines, and finding differences between thecapacitances on each of the drive lines in a direction in which the eachof the drive lines extends, the differences being found as thedifferences in signal between the respective pairs of the sense linesadjacent to each other, the touch panel system further including: adecoding section for decoding the values of the differences between thecapacitances, which differences are found by the subtracting section,the decoding being carried out in such a manner that an inner product ofeach of code sequences for driving the drive lines in parallel and eachof difference output sequences of the sense lines, which differenceoutput sequences correspond to the code sequences, is calculated; and aswitch for switching a signal to be supplied to the subtracting sectionso that the subtracting section finds a first difference which isexpressed by (Sn+1)−Sn or a second difference which is expressed bySn−(Sn−1), the first difference corresponding to a difference between(i) a signal of a sense line Sn which is selected from the plurality ofsense lines and (ii) a signal of a sense line Sn+1, which is one of twosense lines adjacent to the sense line Sn, the two sense lines being thesense line Sn+1 and a sense line Sn−1 each of which is included in theplurality of sense lines, the second difference corresponding to adifference between (i) the signal of the sense line Sn and (ii) a signalof the sense line Sn−1, which is the other one of the two sense lines,the touch panel further including: a plurality of vertical electrodes(i) each including a repeat of first basic shapes connected to oneanother in a vertical direction, the first basic shapes each including afine wire, (ii) provided on a vertical electrode surface, and (iii)arranged at a predetermined interval in a horizontal direction; aplurality of horizontal electrodes (i) each including a repeat of secondbasic shapes connected to one another in the horizontal direction, thesecond basic shapes each including a fine wire, (ii) provided on ahorizontal electrode surface parallel to the vertical electrode surface,and (iii) arranged at a predetermined interval in the verticaldirection; and an insulator provided between the vertical electrodesurface and the horizontal electrode surface so as to insulate theplurality of vertical electrodes and the plurality of horizontalelectrodes from each other, the plurality of vertical electrodes and theplurality of horizontal electrodes (i) being disposed so that, as viewedin a direction perpendicular to the vertical electrode surface, theplurality of vertical electrodes include no segment coincident with theplurality of horizontal electrodes and (ii) forming a uniform gridhaving no gap.

In order to attain the foregoing objects, a further touch panel systemof the present invention includes: a touch panel; and a touch panelcontroller for processing a signal supplied from the touch panel, thetouch panel including a sensor section, the sensor section beingprovided with a plurality of sense lines and detecting a touch operationperformed with respect to the touch panel, the touch panel controllerincluding a subtracting section for (i) receiving signals from thesensor section and (ii) finding differences in signal between, among thesense lines, respective pairs of sense lines adjacent to each other, thetouch panel system further including: drive lines provided so as tointersect the sense lines; a drive line driving circuit for driving thedrive lines in parallel; and capacitances being formed between the senselines and the drive lines, the subtracting section receiving outputsignals from the sense lines, and finding differences between thecapacitances on each of the drive lines in a direction in which the eachof the drive lines extends, the differences being found as thedifferences in signal between the respective pairs of the sense linesadjacent to each other, the touch panel system further including: adecoding section for decoding the values of the differences between thecapacitances, which differences are found by the subtracting section,the decoding being carried out in such a manner that an inner product ofeach of code sequences for driving the drive lines in parallel and eachof difference output sequences of the sense lines, which differenceoutput sequences correspond to the code sequences, is calculated, thetouch panel further including: a plurality of vertical electrodes (i)each including a repeat of first basic shapes connected to one anotherin a vertical direction, the first basic shapes each including a finewire, (ii) provided on a vertical electrode surface, and (iii) arrangedat a predetermined interval in a horizontal direction; a plurality ofhorizontal electrodes (i) each including a repeat of second basic shapesconnected to one another in the horizontal direction, the second basicshapes each including a fine wire, (ii) provided on a horizontalelectrode surface parallel to the vertical electrode surface, and (iii)arranged at a predetermined interval in the vertical direction; and aninsulator provided between the vertical electrode surface and thehorizontal electrode surface so as to insulate the plurality of verticalelectrodes and the plurality of horizontal electrodes from each other,the plurality of vertical electrodes and the plurality of horizontalelectrodes (i) being disposed so that, as viewed in a directionperpendicular to the vertical electrode surface, the plurality ofvertical electrodes include no segment coincident with the plurality ofhorizontal electrodes and (ii) forming a uniform grid having no gap.

According to each of the above configurations, the subtracting sectionobtains difference in signal values between the respective pairs of thesense lines adjacent to each other. Namely, each difference is foundbetween the adjacent sense lines, which have a higher correlation interms of noise. This removes a noise component from the output signalsupplied from the main sensor, thereby extracting a signal derived fromthe touch operation itself. This makes it possible to reliably remove(cancel) a wide variety of noises reflected in the touch panel.

Further, according to each of the above configurations, the touch panelis parallel driven, and the decoding section decodes the values of thedifferences between the capacitances which values are found by thesubtracting section. Consequently, signals of the capacitances aremultiplied by a code length (i.e., multiplied by N). Therefore, signalstrengths of the capacitances are increased, regardless of the number ofdrive lines. Further, provided that necessary signal strengths aremerely equal to those of a conventional driving method, it is possibleto reduce the number of times that the drive lines should be driven.This makes it possible to reduce electric power consumption.

Further, according to each of the above configurations, the abovearrangement disposes (I) a plurality of vertical electrodes (i) eachincluding a repeat of first basic shapes connected to one another in avertical direction, the first basic shapes each including a fine wire,(ii) provided on a vertical electrode surface, and (iii) arranged at apredetermined interval in a horizontal direction and (II) a plurality ofhorizontal electrodes (i) each including a repeat of second basic shapesconnected to one another in the horizontal direction, the second basicshapes each including a fine wire, (ii) provided on a horizontalelectrode surface parallel to the vertical electrode surface, and (iii)arranged at a predetermined interval in the vertical direction so that(i) as viewed in a direction perpendicular to the vertical electrodesurface, the plurality of vertical electrodes include no segmentcoincident with the plurality of horizontal electrodes and that (ii) theplurality of vertical electrodes and the plurality of horizontalelectrodes form a uniform grid having no gap. Thus, preparing anelectrode distribution with (i) the vertical electrodes, (ii) thehorizontal electrodes, and (iii) an insulating film sandwichedtherebetween forms a uniform grid having no visible gap. Such anelectrode distribution, as placed on a display device, can prevent moireand the like from occurring.

In order to attain the foregoing objects, an electronic device of thepresent invention includes a touch panel system of the presentinvention.

Accordingly, it is possible to provide an electronic device capable ofreliably removing (canceling) a wide variety of noises reflected in atouch panel. Further, preparing an electrode distribution with (i) thevertical electrodes, (ii) the horizontal electrodes, and (iii) aninsulating film sandwiched therebetween forms a uniform grid having novisible gap. Such an electrode distribution, as placed on a displaydevice, can prevent moire and the like from occurring.

Advantageous Effects of Invention

As described above, a touch panel system of the present invention isconfigured such that a plurality of vertical electrodes and a pluralityof horizontal electrodes are so disposed that (i) as viewed in thedirection perpendicular to the vertical electrode surface, the pluralityof vertical electrodes include no segment coincident with the pluralityof horizontal electrodes and that (ii) the plurality of verticalelectrodes and the plurality of horizontal electrodes form a uniformgrid having no gap. Accordingly, the present invention provides aneffect of reliably removing (canceling) a wide variety of noisesreflected in a touch panel. Further, the touch panel system, as placedon a display device, can prevent moire and the like from occurring.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view schematically illustrating a basic configuration of atouch panel system according to the present invention.

FIG. 2 is a flow chart illustrating a basic process of the touch panelsystem shown in FIG. 1.

FIG. 3 is a view illustrating waveforms of respective signals which areto be processed by a subtracting section in the touch panel system shownin FIG. 1.

FIG. 4 is a view schematically illustrating a basic configuration ofanother touch panel system according to the present invention.

FIG. 5 is a view schematically illustrating a touch panel which isincluded in another version of the touch panel system shown in FIG. 4and does not include a sub sensor group.

FIG. 6 is a flow chart illustrating a basic process of the touch panelsystem shown in FIG. 4.

FIG. 7 is a view schematically illustrating a basic configuration ofanother touch panel system according to the present invention.

FIG. 8 is a flow chart illustrating a basic process of the touch panelsystem shown in FIG. 7.

FIG. 9 is a view illustrating a driving method of a touch panel whichdriving method is employed in a conventional touch panel system.

FIG. 10 is a view illustrating a driving method (orthogonal sequencedriving method) of a touch panel which driving method is employed in atouch panel system of the present invention.

FIG. 11 is a view illustrating a process which needs to be performed bythe touch panel employing the driving method of FIG. 9 in order toachieve sensitivity equivalent to that of the touch panel employing thedriving method of FIG. 10.

FIG. 12 is a view schematically illustrating another touch panel systemaccording to the present invention, said another touch panel systemincluding a touch panel driven by the orthogonal sequence drivingmethod.

FIG. 13 is a view schematically illustrating a basic configuration of atouch panel system according to another embodiment of the presentinvention.

FIG. 14 is a view schematically illustrating a basic configuration ofanother touch panel system according to the present invention.

FIG. 15 is a view schematically illustrating a basic configuration ofanother touch panel system according to the present invention.

FIG. 16 is a view schematically illustrating a basic configuration ofanother touch panel system according to the present invention.

FIG. 17 is a circuit diagram showing one example of a total differentialamplifier included in the touch panel system shown in FIG. 16.

FIG. 18 is a view schematically illustrating a basic configuration ofanother touch panel system according to the present invention.

FIG. 19 is a block diagram illustrating a noise processing sectionprovided in a touch panel system of Patent Literature 1.

FIG. 20 is a view schematically illustrating a basic configuration ofanother touch panel system according to the present invention.

FIG. 21 is a flow chart illustrating a basic process of the touch panelsystem shown in FIG. 20.

FIG. 22 is a view schematically illustrating a basic configuration ofanother touch panel system according to the present invention.

FIG. 23 is a view schematically illustrating a basic configuration ofanother touch panel system according to the present invention.

FIG. 24 is a view schematically illustrating a basic configuration ofanother touch panel system according to the present invention.

FIG. 25 is a view schematically illustrating a basic configuration ofanother touch panel system according to the present invention.

FIG. 26 is a view schematically illustrating a basic configuration ofanother touch panel system according to the present invention.

FIG. 27 is a flow chart illustrating a basic process of a judgingsection in the touch panel system shown in FIG. 22.

FIG. 28 is a view schematically illustrating a method of recognizingtouch information in the flow chart shown in FIG. 27.

FIG. 29 is a functional block diagram illustrating a configuration of amobile phone including the touch panel system.

FIG. 30 is a block diagram illustrating a configuration of a touchsensor system of Embodiment 18.

FIG. 31 is a cross-sectional view illustrating a structure of a touchpanel included in the touch sensor system.

FIG. 32

(a) is a diagram illustrating a first basic shape of a verticalelectrode included in the touch panel, and (b) is a diagram illustratingan arrangement of vertical electrodes.

FIG. 33

(a) is a diagram illustrating a second basic shape of a horizontalelectrode included in the touch panel, and (b) is a diagram illustratingan arrangement of horizontal electrodes.

FIG. 34 is a diagram illustrating a uniform grid including the verticalelectrodes and the horizontal electrode.

FIG. 35

(a) is a diagram illustrating a first basic shape of a verticalelectrode included as a variation in the touch panel, and (b) is adiagram illustrating an arrangement of vertical electrodes according tothe variation.

FIG. 36

(a) is a diagram illustrating a second basic shape of a horizontalelectrode included as a variation in the touch panel, and (b) is adiagram illustrating an arrangement of horizontal electrodes accordingto the variation.

FIG. 37 is a diagram illustrating a uniform grid including the verticalelectrodes according to the variation and the horizontal electrodeaccording to the variation.

FIG. 38

(a) is a diagram illustrating a configuration of a first basic shape ofa vertical electrode according to the variation, the first basic shapebeing filled with a transparent electrode material, and (b) is a diagramillustrating vertical electrodes according to the variation, thevertical electrodes being filled with the transparent electrodematerial.

FIG. 39

(a) is a diagram illustrating a configuration of a second basic shape ofa horizontal electrode according to the variation, the second basicshape being filled with a transparent electrode material, and (b) is adiagram illustrating horizontal electrodes according to the variation,the horizontal electrodes being filled with the transparent electrodematerial.

FIG. 40

(a) is a diagram illustrating an arrangement of the vertical electrodesaccording to the variation, the vertical electrodes being connected torespective address lines, (b) is a diagram illustrating an arrangementof the horizontal electrodes according to the variation, the horizontalelectrodes being connected to respective address lines, and (c) is adiagram illustrating a grid including the vertical electrodes connectedto the respective address lines and the horizontal electrodes connectedto the respective address lines.

FIG. 41

(a) is a diagram illustrating a first basic shape of a verticalelectrode included in a touch panel of Embodiment 19, and (b) is adiagram illustrating an arrangement of vertical electrodes.

FIG. 42

(a) is a diagram illustrating a second basic shape of a horizontalelectrode included in the touch panel of Embodiment 19, and (b) is adiagram illustrating an arrangement of horizontal electrodes.

FIG. 43

(a) is a diagram illustrating a first basic shape of a verticalelectrode included in a touch panel of Embodiment 20, and (b) is adiagram illustrating an arrangement of vertical electrodes.

FIG. 44

(a) is a diagram illustrating a second basic shape of a horizontalelectrode included in the touch panel of Embodiment 20, and (b) is adiagram illustrating an arrangement of horizontal electrodes.

FIG. 45

(a) is a diagram illustrating a first basic shape of a verticalelectrode included in a touch panel of Embodiment 21, and (b) is adiagram illustrating an arrangement of vertical electrodes.

FIG. 46

(a) is a diagram illustrating a second basic shape of a horizontalelectrode included in the touch panel of Embodiment 21, and (b) is adiagram illustrating an arrangement of horizontal electrodes.

FIG. 47

(a) is a diagram illustrating a first basic shape of a verticalelectrode included in a touch panel of Embodiment 22, and (b) is adiagram illustrating an arrangement of vertical electrodes.

FIG. 48

(a) is a diagram illustrating a second basic shape of a horizontalelectrode included in the touch panel of Embodiment 22, and (b) is adiagram illustrating an arrangement of horizontal electrodes.

FIG. 49 is a diagram illustrating a uniform grid including the verticalelectrodes and the horizontal electrode.

FIG. 50

(a) is a diagram illustrating a first basic shape of another verticalelectrode included in the touch panel of Embodiment 22, and (b) is adiagram illustrating an arrangement of such other vertical electrodes.

FIG. 51

(a) is a diagram illustrating a second basic shape of another horizontalelectrode included in the touch panel of Embodiment 22, and (b) is adiagram illustrating an arrangement of such other horizontal electrodes.

FIG. 52

(a) is a diagram illustrating a first basic shape of a verticalelectrode included as a variation in the touch panel, and (b) is adiagram illustrating a second basic shape of a horizontal electrodeincluded as a variation in the touch panel.

FIG. 53

(a) is a diagram illustrating a first basic shape of a verticalelectrode included as another variation in the touch panel, and (b) is adiagram illustrating a second basic shape of a horizontal electrodeincluded as another variation in the touch panel.

FIG. 54 is a diagram illustrating an appearance of an electronicblackboard of Embodiment 23.

FIG. 55 is a diagram illustrating an arrangement of vertical electrodesand horizontal electrodes in a conventional capacitive touch sensorpanel.

FIG. 56 is a diagram illustrating an arrangement of vertical electrodesand horizontal electrodes in another conventional capacitive touchsensor panel.

FIG. 57

(a) is a diagram illustrating an arrangement of vertical electrodes inyet another conventional capacitive touch sensor panel, and (b) is adiagram illustrating an arrangement of horizontal electrodes in thatcapacitive touch sensor panel.

FIG. 58 is a diagram illustrating a uniform grid including the verticalelectrodes and the horizontal electrode.

FIG. 59

(a) is a diagram illustrating an arrangement of vertical electrodes instill another conventional capacitive touch sensor panel, and (b) is adiagram illustrating an arrangement of horizontal electrodes in thatcapacitive touch sensor panel.

DESCRIPTION OF EMBODIMENTS

The following will describe embodiments of the present invention withreference to drawings.

Embodiment 1 (1) Configuration of Touch Panel System 1

FIG. 1 is a view schematically illustrating a basic configuration of atouch panel system 1 according to one embodiment of the presentinvention. The touch panel system 1 includes a display device 2, a touchpanel 3, a touch panel controller 4, and a drive line driving circuit 5.Further, the touch panel system 1 has a noise canceling function. In thedescriptions below, a side used by a user is referred to as a “frontsurface” (or an “upper side”).

The display device 2 includes a display screen (display section), whichis not illustrated in FIG. 1. The display screen displays, e.g., variouskinds of icons for operation and text information corresponding tooperation instructions for the user. The display device 2 is made of,e.g., a liquid crystal display, a plasma display, an organic EL display,or a field emission display (FED). These displays are used in manygenerally-used electronic devices. Therefore, making the display device2 of such the display provides a touch panel system 1 having a greatversatility. The display device 2 may have any configuration, and is notlimited to any particular configuration.

The touch panel 3 is configured to allow the user to perform a touch(press) operation on a surface of the touch panel 3 by his/her finger, astylus, or the like so as to enter various kinds of operationinstructions. The touch panel 3 is stacked on a front surface (upperside) of the display device 2 so as to cover the display screen.

The touch panel 3 includes two sensors (one main sensor 31 and one subsensor 32) which are provided on (in) the same surface. The main sensor31 and the sub sensor 32 are provided so as to be adjacent to eachother. Each of the main sensor 31 and the sub sensor 32 is a capacitivetype sensor. The touch panel 3, which is provided with the capacitivetype sensors, has an advantage of having high transmittance and havingdurability.

The main sensor (main sensor section) 31 is provided in a region(touched region) of the touch panel 3 in which region a touch operationis performed. The main sensor 31 detects a touch operation that the userperforms with respect to the touch panel 3. The touch operation is, forexample, double-click, sliding, single-click, or dragging. The mainsensor 31 is provided with a sense line 33 which is made of a linearelectrode. The sense line 33 has an end which is connected with thetouch panel controller 4. With this, a signal detected by the mainsensor 31 is outputted to the touch panel controller 4 via the senseline 33. Namely, a signal corresponding to a touch operation detected bythe main sensor 31 is outputted to the touch panel controller 4.

The sub sensor (sub sensor section) 32 detects a noise componentreflected in the touch panel 3. The sub sensor 32 is provided in aregion (non-touched region) of the touch panel 3 in which region notouch operation is performed. Therefore, the sub sensor 32 is nottouched by the user in a touch operation, and the sub sensor 32 detectsvarious kinds of noises generated in the touch panel system 1. Thus,unlike the main sensor 31, the sub sensor 32 does not detect a signalcorresponding to a touch operation. Namely, the sub sensor 32 isconfigured not to be touched by the user in a touch operation and todetect a noise generated in the touch panel 3.

The sub sensor 32 is provided with a sub sense line 34 which is made ofa linear electrode. The sub sense line 34 is provided so as to extend inparallel with the sense line 33 (i.e., to extend along a direction inwhich the sense line 33 extends). The sub sense line 34 has an end whichis connected with the touch panel controller 4. With this, a signaldetected by the sub sensor 32 is outputted to the touch panel controller4 via the sub sense line 34.

Meanwhile, the touch panel 3 includes a drive line 35 provided so as tointersect the sense line 33 and the sub sense line 34 at right angles.The drive line 35 is made of a linear electrode. A capacitance is formedin an intersection of the sense line 33 or the sub sense line 34 and thedrive line 35. Namely, a capacitance is formed in an intersection of thesense line 33 and the drive line 35, and another capacitance is formedin an intersection of the sub sense line 34 and the drive line 35. Thedrive line 35 is connected with the drive line driving circuit (sensordriving section) 5. Upon activation of the touch panel system 1, thedrive line 35 is supplied with an electric potential at a certaininterval.

Each of the sense line 33, the sub sense line 34, and the drive line 35can be made of, e.g., a transparent wire material such as ITO (IndiumTin Oxide). In other words, each of the sense line 33, the sub senseline 34, and the drive line 35 is a sensor electrode in the touch panel3.

Note that the drive line 35 is provided on a transparent substrate or atransparent film (not illustrated). Further, the drive line 35 iscovered with an insulative layer (not illustrated). On the insulativelayer, the sense line 33 and the sub sense line 34 are provided. Thus,the sense line 33 or the sub sense line 34 and the drive line 35 areisolated from each other via the insulative layer, and the sense line 33or the sub sense line 34 and the drive line 35 are coupled to each othervia the capacitance. The sense line 33 and the sub sense line 34 arecovered with a protective layer (not illustrated). Namely, in the touchpanel 3, the protective layer is positioned so as to be the closest tothe front surface side (the user's side).

The touch panel controller 4 reads signals (data) supplied from the mainsensor 31 and the sub sensor 32 of the touch panel 3. Since the touchpanel system 1 includes the capacitive type sensors, the touch panelcontroller 4 detects a capacitance generated in the touch panel 3.Concretely, the touch panel controller 4 detects (i) a change in thecapacitance between the sense line 33 and the drive line 35 and (ii) achange in the capacitance between the sub sense line 34 and the driveline 35. The touch panel controller 4 includes a subtracting section 41,a coordinates detecting section 42, and a CPU 43.

The subtracting section 41 includes (i) an input terminal (i.e., aninput terminal for a main sensor output) for receiving a signaloutputted by the main sensor 31 and (ii) an input terminal (i.e., aninput terminal for a sub sensor output) for receiving a signal outputtedby the sub sensor 32. The subtracting section 41 subtracts (i) thesignal supplied to the input terminal for the sub sensor output from(ii) the signal supplied to the input terminal for the main sensoroutput. The signal obtained as a result of the subtracting operation bythe subtracting section 41 is outputted to the coordinates detectingsection 42. Note that the signal supplied to the subtracting section 41may be either of a digital signal and an analog signal. Namely, theinput signal supplied to the subtracting section 41 may be any signal,as long as it suits with the configuration of the subtracting section41.

According to the signal obtained as a result of the subtractingoperation by the subtracting section 41, the coordinates detectingsection 42 detects information indicative of the presence or absence ofa touch operation. For example, if a value of the output signal suppliedfrom the subtracting section 41 is equal to or greater than apredetermined threshold value, the coordinates detecting section 42outputs, to the CPU 43, a signal indicative of the presence of a touchoperation. Note that the touch panel system 1 includes a single mainsensor 31; therefore, the coordinates detecting section 42 detectsinformation indicative of the presence or absence of a touch operation.Meanwhile, if a touch panel system 1 is configured to include aplurality of main sensors 31, a coordinates detecting section 42determines, in addition to the presence or absence of a touch operation,coordinates values indicative of a position touched by the user.

The CPU 43 obtains, at a certain interval, information outputted by thecoordinates detecting section 42. Further, according to the informationthus obtained, the CPU 43 performs an operation such as output of theinformation to the display device 2.

The drive line driving circuit 5 is connected with the drive line 35.Upon activation of the touch panel system 1, the drive line drivingcircuit 5 applies an electric potential to the drive line 35 at acertain interval.

(2) Noise Processing Performed by Touch Panel System 1

The touch panel system 1 determines, according to a change in thecapacitance which change is detected by the touch panel controller 4,the presence or absence of a touch operation. However, since the touchpanel 3 is bonded to the front surface (the user's side) of the displaydevice 2, the touch panel system 1 is likely to be affected not only bya noise such as a clock generated in the display device 2 but also byother noises coming from the outside. This leads to impairment indetection sensitivity for a touch operation (i.e., detection sensitivityof the coordinates detecting section 42).

In order to address this, as a measure for removing such the noises, thetouch panel system 1 includes the sub sensor 32 and the subtractingsection 41. With reference to FIG. 2, a noise canceling process of thetouch panel system 1 will be described. FIG. 2 is a flow chartillustrating a noise canceling process, which is a basic process of thetouch panel system 1.

Upon activation of the touch panel system 1, the drive line drivingcircuit 5 applies an electric potential to the drive line 35 at acertain interval. When the user performs a touch operation on the touchpanel 3, both of the main sensor 31 and the sub sensor 32 output signalsto the subtracting section 41.

Here, (i) a noise such as a clock generated in the display device 2 and(ii) other noises coming from the outside are reflected in the touchpanel 3. Therefore, various kinds of noise components are detected bythe main sensor 31 and the sub sensor 32. Namely, the output signalsupplied from the main sensor 31 includes not only a signal derived fromthe touch operation itself but also a noise signal (noise component).Meanwhile, since the sub sensor 32 is configured not to detect any touchoperation, the output signal supplied from the sub sensor 32 includes anoise signal (noise component), but does not include a signal derivedfrom the touch operation (F201).

In the touch panel system 1, the main sensor 31 and the sub sensor 32are provided in the same surface so as to be adjacent to each other.Therefore, (i) a value of the noise signal included in the output signalsupplied from the main sensor 31 and (ii) a value of the noise signalincluded in the output signal supplied from the sub sensor 32 can beregarded as being basically the same. In view of this, the subtractingsection 41 included in the touch panel controller 4 executes anoperation for subtracting (i) the input signal (signal value) suppliedfrom the sub sensor 32 from (ii) the input signal (signal value)supplied from the main sensor 31 (F202). Namely, the subtracting section41 finds a difference between the sense line 33 and the sub sense line34. This removes the noise signal from the output signal supplied fromthe main sensor 31. This provides the signal value derived from thetouch operation itself, which signal value is generated in response tothe touch operation.

The signal thus obtained by the subtracting operation (the signalderived from the touch operation itself) is outputted to the coordinatesdetecting section 42 included in the touch panel controller 4 (F203).Namely, the signal derived from the touch operation itself is outputtedto the coordinates detecting section 42. According to the signal derivedfrom the touch operation itself, the coordinates detecting section 42determines the presence or absence of a touch operation. With thisconfiguration, it is possible to prevent impairment in detectionsensitivity of the coordinates detecting section 42 (e.g., detectionsensitivity as to the presence or absence of a touch operation).

Thus, according to the touch panel system 1, the subtracting section 41finds a difference between the sense line 33 and the sub sense line 34,so as to cancel, from an input signal which is supplied from the senseline 33 and includes a wide variety of noise components, the noisecomponents. Namely, the subtracting section 41 cancels a noise signalfrom an input signal supplied from the sense line 33, so as to extract asignal derived from a touch operation itself. Thus, it is possible toprovide the touch panel system 1 capable of reliably canceling a widevariety of noises.

The noise canceling process of the touch panel system 1 is visuallyillustrated in FIG. 3. FIG. 3 is a view illustrating waveforms ofrespective signals which are to be processed by the subtracting section41 in the touch panel system 1. (a) of FIG. 3 shows an output signalsupplied from the main sensor 31, (b) of FIG. 3 shows an output signalsupplied from the sub sensor 32, and (c) of FIG. 3 is a signal processedby the subtracting section 41. Each signal shown in FIG. 3 is a signalgenerated in response to a touch operation performed by the user.

The touch panel system 1 is configured such that the user's performing atouch operation increases the capacitance of the main sensor 31 whichdetects a touch operation ((a) of FIG. 3). Namely, the user's performinga touch operation increases a value of an output signal supplied fromthe main sensor 31 (the sense line 33). However, the output signalsupplied from the main sensor 31 in response to the touch operationincludes not only (i) a signal derived from the touch operation itselfbut also (ii) various kinds of noise signals (e.g., a noise such as aclock generated in the display device 2 and/or a noise coming from theoutside).

Meanwhile, since the sub sensor 32 does not detect a touch operation,the capacitance of the sub sensor 32 (the sub sense line) is notincreased by the touch operation. Namely, an output signal supplied fromthe sub sensor 32 does not include a signal derived from the touchoperation, but includes a noise component reflected in the touch panel 3((b) of FIG. 3).

The subtracting section 41 subtracts (i) the output signal supplied fromthe sub sensor 32 from (ii) the output signal supplied from the mainsensor 31 (i.e., the signal value of (a) of FIG. 3−the signal value of(b) of FIG. 3). As shown in (c) of FIG. 3, this subtracting operationremoves (i) the noise component outputted by the sub sensor 32 from (ii)the output signal supplied from the main sensor 31. This provides thesignal derived from the touch operation itself, which signal isgenerated in response to the touch operation. Furthermore, since thecoordinates detecting section 42 is supplied with the signal derivedfrom the touch operation itself, detection accuracy for a touchoperation is not impaired.

As described above, according to the touch panel system 1 of the presentembodiment, the main sensor 31 and the sub sensor 32 are provided in(on) the same surface of the touch panel 3. Consequently, each of (i) anoutput signal supplied from the main sensor 31 and (ii) an output signalsupplied from the sub sensor 32 includes various kinds of noise signalsreflected in the touch panel 3. Furthermore, the subtracting section 41finds a difference between (i) the output signal supplied from the mainsensor 31 which signal includes a signal derived from a touch operationand a noise signal and (ii) the output signal supplied from the subsensor 32 which signal includes a noise signal. This removes the noisecomponent from the output signal supplied from the main sensor 31,thereby extracting the signal derived from the touch operation itself.Therefore, it is possible to reliably remove (cancel) a wide variety ofnoises reflected in the touch panel 3.

Note that, according to the touch panel system of Patent Literature 1, anoise component which is the subject of removal is an AC signalcomponent included in a signal which includes noise components. On theother hand, according to the touch panel system 1, each of (i) an outputsignal supplied from the main sensor 31 and (ii) an output signalsupplied from the sub sensor 32 includes various kinds of noisecomponents. Therefore, according to the touch panel system 1, a noisecomponent which is the subject of removal is not limited to an AC signalcomponent. Thus, the touch panel system 1 can cancel all noisesreflected in the touch panel 3.

In the touch panel system 1, the sub sensor 32 only needs to be providedin a surface of the touch panel 3 in which surface the main sensor 31 isalso provided. With this configuration, both of the main sensor 31 andthe sub sensor 32 can detect a noise component (noise signal) reflectedin the touch panel 3. Note that the sub sensor 32 is preferablyconfigured not to detect a touch operation performed on the touch panel3. With this configuration, the sub sensor 32 does not detect a signalderived from a touch operation; therefore, an output signal suppliedfrom the sub sensor 32 does not include the signal derived from thetouch operation. This prevents a case where the signal value derivedfrom the touch operation is reduced by the subtracting operationperformed by the subtracting section 41. Namely, the noise component isremoved without reducing the signal derived from the touch operationwhich signal is detected by the main sensor 31. Therefore, it ispossible to further enhance detection sensitivity for a touch operation.

The touch panel system 1 is configured such that the sub sensor 32 isprovided in the region (non-touched region) of the touch panel 3 inwhich region no touch operation is performed by the user. In such aconfiguration, a signal derived from a touch operation is not detectedby the sub sensor 32. Therefore, on the sub sensor 32, the user wouldnot perform a touch operation. Accordingly, although the sub sensor 32detects a noise reflected in the touch panel, the sub sensor 32 does notdetect the signal derived from the touch operation. Thus, it is possibleto reliably prevent the sub sensor 32 from detecting a touch operation.

In order that the sub sensor 32 detects a noise component, the subsensor 32 is preferably provided as close to the main sensor 31 aspossible. More preferably, the sub sensor 32 and the main sensor 31 arearranged side by side so as to be in contact with each other. With thisconfiguration, the main sensor 31 and the sub sensor 32 are providedunder almost the same condition. Particularly in a configuration inwhich the sub sensor 32 and the main sensor 31 are arranged side by sideso as to be in contact with each other, the main sensor 31 and the subsensor 32 are arranged so that a distance therebetween is shortest.Therefore, a value of a noise signal included in an output signalsupplied from the sub sensor 32 can be regarded as being the same asthat of a noise signal included in an output signal supplied from themain sensor 31. Therefore, by the subtracting operation performed by thesubtracting section 41, it is possible to more reliably remove a noisecomponent reflected in the touch panel 3. This makes it possible tofurther enhance detection sensitivity for a touch operation.

The present embodiment has dealt with the touch panel system 1 includingthe touch panel 3 of capacitive type. However, the principle ofoperation of the touch panel 3 (i.e., the method of operating thesensor) is not limited to the capacitive type. For example, the noisecanceling function can be achieved similarly by a touch panel systemincluding a touch panel of resistance film type, infrared type,ultrasonic wave type, or electromagnetic induction coupling type.Further, regardless of the type of the display device 2, the touch panelsystem 1 of the present embodiment provides the noise cancelingfunction.

The touch panel system 1 of the present embodiment is applicable tovarious kinds of electronic devices provided with touch panels. Examplesof such the electronic device encompass televisions, personal computers,mobile phones, digital cameras, portable game devices, electronic photoframes, personal digital assistants (PDAs), electronic books, homeelectronic appliances (e.g., microwave ovens, washing machines), ticketvending machines, automatic teller machines (ATM), and car navigationsystems. Thus, it is possible to provide an electronic device which iscapable of effectively preventing impairment in detection sensitivityfor a touch operation.

Embodiment 2 (1) Configuration of Touch Panel System 1 a

FIG. 4 is a view schematically illustrating a basic configuration of atouch panel system 1 a according to another embodiment of the presentinvention. A basic configuration of the touch panel system 1 a issubstantially the same as that of the touch panel system 1 ofEmbodiment 1. The following will describe the touch panel system 1 a,focusing on differences between the touch panel system 1 a and the touchpanel system 1. For convenience of explanation, members having the samefunctions as those explained in the drawings described in Embodiment 1are given the same reference signs, and explanations thereof are omittedhere.

The touch panel system 1 a differs from the touch panel system 1 interms of configurations of sensors provided in a touch panel 3 a.Specifically, the touch panel 3 a includes (i) a main sensor group 31 amade of a plurality of main sensors 31 and (ii) a sub sensor group 32 amade of a plurality of sub sensors 32. The touch panel system 1 adetects not only (i) the presence or absence of a touch operationperformed by the user but also (ii) positional information (coordinates)indicative of a position where the user performs the touch operation.

Specifically, according to the touch panel system 1 a, the touch panel 3a includes the main sensor group 31 a and the sub sensor group 32 awhich are provided on (in) the same surface of the touch panel 3 a. Themain sensor group 31 a and the sub sensor group 32 a are provided so asto be adjacent to each other. Each of the main sensor group 31 a and thesub sensor group 32 a is made of capacitive type sensors.

The main sensor group (main sensor section) 31 a is provided in a region(touched region) of the touch panel 3 a in which region a touchoperation is performed. The main sensor group 31 a detects a touchoperation that the user performs with respect to the touch panel 3 a.The main sensor group 31 a is made of the plurality of main sensors 31which are arranged in a matrix. The main sensor group 31 a is providedwith L sense lines 33 (L is an integer of 2 or greater). The sense lines33 are provided so as to be parallel with each other and evenly spaced.On each of the sense lines 33, M main sensors 31 are provided (M is aninteger of 2 or greater).

Each of the sense lines 33 has an end which is connected with asubtracting section 41 of a touch panel controller 4. With this, asignal detected by each main sensor is outputted to the subtractingsection 41 via its corresponding sense line 33. Namely, a signalcorresponding to a touch operation detected by the main sensor 31 isoutputted to the subtracting section 41.

The sub sensor group (sub sensor section) 32 a detects a noise componentreflected in the touch panel 3 a. The sub sensor group 32 a is providedin a region (non-touched region) of the touch panel 3 a in which regionno touch operation is performed. Therefore, the sub sensor group 32 a isnot touched by the user in a touch operation, and the sub sensor group32 a detects various kinds of noises generated in the touch panel system1 a. Thus, unlike the main sensor group 31 a, the sub sensor group 32 adoes not detect a signal corresponding to a touch operation. Namely, thesub sensor group 32 a is configured not to be touched by the user in atouch operation but to detect a noise generated in the sensor. The subsensor group 32 a is provided with one sub sense line 34. The sub senseline 34 is provided so as to extend in parallel with the sense lines 33(i.e., to extend along a direction in which the sense lines 33 extend).On the sub sense line 34, M sub sensors 32 are provided (M is an integerof 2 or greater). Namely, the number of main sensors 31 provided on eachsense line 33 is equal to the number of sub sensors 32 provided on thesub sense line 34.

The sub sense line 34 has an end which is connected with the subtractingsection 41 of the touch panel controller 4. With this, a signal detectedby the sub sensor group 32 a is outputted to the subtracting section 41via the sub sense line 34.

Meanwhile, the touch panel 3 a includes M drive lines 35 provided so asto intersect the sense lines 33 and the sub sense line 34 at rightangles (M is an integer of 2 or greater). The drive lines 35 areprovided so as to extend in parallel with each other and to be evenlyspaced. On each of the drive lines 35, L main sensors 31 and one subsensor 32 are provided (L is an integer of 2 or greater). Further, acapacitance is formed in an intersection of each of the sense lines 33or the sub sense line 34 and a corresponding one of the drive lines 35.Namely, capacitances are formed in intersections of the sense lines 33and the drive lines 35, and capacitances are formed in intersections ofthe sub sense line 34 and the drive lines 35. The drive lines 35 areconnected with a drive line driving circuit (not illustrated). Uponactivation of the touch panel system 1 a, the drive lines 35 aresupplied with electric potentials at a certain interval.

Thus, in the touch panel 3 a, (i) the sense lines 33 and the sub senseline 34, which are provided in a horizontal direction, and (ii) thedrive lines 35, which are provided in a vertical direction, are arrangedin a two-dimensional matrix. For the sense line 33, the sub sense lines34, and the drive line 35, the number thereof, a length thereof, a widththereof, a space therebetween, and/or the like can be arbitrarily setaccording to the intended purpose of the touch panel system 1 a, thesize of the touch panel 3 a, and/or the like.

(2) Noise Processing Performed by Touch Panel System 1 a

The touch panel system 1 a determines, according to a change in thecapacitance which change is detected by the touch panel controller 4,(i) the presence or absence of a touch operation and (ii) a touchedposition. However, similarly to the touch panel system 1, the touchpanel system 1 a is likely to be affected by various kinds of noises.This leads to impairment in detection sensitivity for a touch operation(i.e., detection sensitivity of the coordinates detecting section).Specifically, FIG. 5 is a view schematically illustrating a touch panel3 b, which is made by modifying the touch panel of the touch panelsystem 1 a shown in FIG. 4 so that it does not include the sub sensorgroup 32 a. As shown in FIG. 5, the touch panel 3 b includes only a mainsensor group 31 a but does not include a sub sensor group 32 a. Namely,the touch panel 3 b shown in FIG. 5 has a configuration which is notprovided with a countermeasure against noises yet. According to thisconfiguration, the touch panel 3 b is affected by various kinds ofnoises. Accordingly, a signal outputted by each sense line 33 includesvarious kinds of noises, and thus detection sensitivity for a touchoperation is impaired.

In order to avoid this, the touch panel system 1 a includes, as ameasure for removing such the noises, the sub sensor group 32 a and thesubtracting section 41. With reference to FIG. 6, the following willdescribe a noise canceling process performed by the touch panel system 1a. FIG. 6 is a flow chart illustrating a noise canceling process, whichis a basic process of the touch panel system 1 a.

Upon activation of the touch panel system 1 a, the drive line 35 issupplied with an electric potential at a certain interval. When the userperforms a touch operation on the touch panel 3 a, both of the mainsensor group 31 a and the sub sensor group 32 a output signals to thesubtracting section 41. Specifically, the user's performing the touchoperation increases a capacitance of a specific main sensor 31corresponding to the touched position. Namely, the user's performing thetouch operation increases a value of an output signal supplied from thatmain sensor 31 (sense line 33). The touch panel system 1 a outputs, tothe subtracting section 41, output signals supplied from the sense line33 and the sub sense line 34, while driving the drive lines 35.

To be more specific, a noise such as a clock generated in the displaydevice 2 and other noises coming from the outside are reflected in thetouch panel 3 a. Therefore, the main sensor group 31 a and the subsensor group 32 a detect various kinds of noise components.Specifically, the output signal supplied from the main sensor group 31 aincludes not only a signal derived from the touch operation itself butalso a noise signal (noise component). Meanwhile, the sub sensor group32 a is configured not to detect a touch operation. Therefore, theoutput signal supplied from the sub sensor group 32 a includes a noisesignal (noise component), but does not include a signal derived from thetouch operation (F501).

In the touch panel system 1 a, the main sensor group 31 a and the subsensor group 32 a are provided in the same surface so as to be adjacentto each other. Therefore, (i) a value of a noise signal included in theoutput signal supplied from the main sensor group 31 a and (ii) a valueof a noise signal included in the output signal supplied from the subsensor group 32 a can be regarded as being basically the same. In viewof this, the subtracting section 41 in the touch panel controller 4executes an operation for subtracting (i) the input signal (signalvalue) supplied from the sub sensor group 32 a from (ii) the inputsignal (signal value) supplied from the main sensor group 31 a (F502).Namely, the subtracting section 41 finds a difference between each senseline 33 and the sub sense line 34. This removes the noise signal fromthe output signal supplied from the main sensor group 31 a. Thisprovides the signal value derived from the touch operation itself, whichsignal is generated in response to the touch operation.

The signal thus obtained by the subtracting operation is outputted tothe coordinates detecting section 42 included in the touch panelcontroller 4 (F503). Thus, the signal derived from the touch operationitself is outputted to the coordinates detecting section 42. Accordingto the signal derived from the touch operation itself, the coordinatesdetecting section 42 detects (i) the presence or absence of a touchoperation and (ii) a touched position (coordinates). With thisconfiguration, it is possible to prevent impairment in detectionsensitivity of the coordinates detecting section 42 (e.g., detectionaccuracy as to the presence or absence of a touch operation, detectionsensitivity as to a touched position).

Note that, according to the touch panel system 1 a, an output signal ofthe sense line 33 provided with the specific main sensor 31corresponding to the touched position has a waveform as shown in (a) ofFIG. 3, whereas an output signal of the sub sensor group 32 a (sub senseline 34) has a waveform as shown in (b) of FIG. 3. The subtractingsection 41 subtracts, from the output signal supplied from the mainsensor group 31 a, the output signal supplied from the sub sensor group32 a. As shown in (c) of FIG. 3, this subtracting operation removes,from the output signal supplied from the main sensor group 31 a, thenoise component outputted by the sub sensor group 32 a. This providesthe signal derived from the touch operation itself, which signal isgenerated in response to the touch operation. Furthermore, since thecoordinates detecting section 42 is supplied with the signal derivedfrom the touch operation itself, detection accuracy for a touchoperation is not impaired. Therefore, it is possible to reduce adifference between (i) the actual touched position and (ii) the detectedposition which is detected by the coordinates detecting section 42.

As described above, while driving the drive lines 35, the touch panelsystem 1 a reads, from the sense line 33, a change in a capacitancevalue of the main sensor group 31 a which change is caused by the touchoperation performed by the user. Furthermore, the touch panel system 1 areads a noise component from the sub sense line 34. Moreover, the touchpanel system 1 a allows the subtracting section 41 to find a differencebetween the sense line 33 and the sub sense line 34, so as to remove(cancel) the noise component.

The touch panel system 1 a includes the main sensor group 31 a made ofthe plurality of main sensors 31 arranged vertically and horizontally inthe form of a matrix. Thanks to this configuration, in addition to thesame effects as those given by the touch panel system 1, the touch panelsystem 1 a can detect, by the coordinates detecting section 42,coordinates indicative of a touched position. Namely, the touch panelsystem 1 a can detect a touched position (coordinates value) in additionto the presence or absence of a touch operation.

As with the case of the touch panel system 1, for the touch panel system1 a, a noise component which is the subject of removal is not limited toan AC signal component. Accordingly, the touch panel system 1 a also cancancel all noises reflected in the touch panel 3 a.

Embodiment 3 (1) Configuration of Touch Panel System 1 b

FIG. 7 is a view schematically illustrating a basic configuration of atouch panel system 1 b according to another embodiment of the presentinvention. A basic configuration of the touch panel system 1 b issubstantially the same as that of the touch panel system 1 a ofEmbodiment 2. The following will describe the touch panel system 1 b,focusing on differences between the touch panel system 1 a and the touchpanel system 1 b. For convenience of explanation, members having thesame functions as those explained in the drawings described inEmbodiments 1 and 2 are given the same reference signs, and explanationsthereof are omitted here.

A touch panel 3 b has the same configuration of that of the touch panel3 a in the touch panel system 1 a of Embodiment 2. Namely, the touchpanel 3 b includes (i) a plurality of drive lines 35 (in FIG. 7, fivedrive lines 35), (ii) a plurality of sense lines 33 (in FIG. 7, sevensense lines 33) intersecting the drive lines 35, and (iii) one sub senseline 34 which intersects the drive lines 35 at right angles and extendsin parallel with the sense lines 33. The sense lines 33 and the drivelines 35 are isolated from each other, and are coupled to each other viacapacitances. The sub sense line 34 and the drive lines 35 are isolatedfrom each other, and are coupled to each other via capacitances.

In the following description, eight sense/sub sense arrays, includingthe one sub sense line 34 and the seven sense lines 33, are referred toas Arrays (1) through (8), respectively.

A touch panel controller 4 includes switches SW, a subtracting section41, storage sections 45 a through 45 d, and an adding section 46, whichare arranged in this order from an input-receiving side of the touchpanel controller 4. Note that the touch panel controller 4 also includesa coordinates detecting section 42 (not illustrated) and a CPU 43 (notillustrated) (FIG. 1). Thus, the touch panel system 1 b differs from thetouch panel systems 1 and 1 a in terms of the configuration of the touchpanel controller 4.

The switches SW select, from signals supplied from the sense lines 33and the sub sense line 34, signals to be supplied to the subtractingsection 41. More specifically, each of the switches SW includes twoterminals (upper and lower terminals), and selects one of the upper andlower terminals. FIG. 7 shows a state where the switches SW select thelower terminals.

The subtracting section 41 performs difference signal operations on, outof signals supplied from Arrays (1) through (8), signals selected by theswitches SW. Specifically, the subtracting section 41 performsdifference signal operations between sense lines 33 which are adjacentto each other, and between a sense line 33 and the sub sense line 34which are adjacent to each other. For example, in a case where theswitches SW select the lower terminals as shown in FIG. 7, thesubtracting section 41 performs the following difference signaloperations: Array (8)−Array (7); Array (6)−Array (5); Array (4) −Array(3); and Array (2)−Array (1). On the other hand, in a case where theswitches SW select the upper terminals (not illustrated), thesubtracting section 41 performs the following difference signaloperations: Array (7)−Array (6); Array (5)−Array (4); and Array(3)−Array (2).

In a case where each of the switches SW selects one of the upper andlower terminals, the storage sections 45 a through 45 d store signals(difference operation signals) obtained by the difference operationsperformed by the subtracting section 41. The difference operationsignals stored in the storage sections 45 a through 45 d are outputtedto the adding section 46. On the other hand, in a case where each of theswitches SW selects the other one of the upper and lower terminals,difference operation signals are directly outputted to the addingsection 46, not via the storage sections 45 a through 45 d.

The adding section 46 adds up the difference operation signals each ofwhich is obtained from the sense lines 33 adjacent to each other andwhich are supplied from the subtracting section 41 and the storagesections 45 a through 45 d. Thereafter, the adding section 46 outputs aresult of the adding operation. Further, the adding section 46 outputsthe difference operation signal (Array (2)−Array (1)) which is obtainedfrom the sub sense line 34 and the sense line 33 adjacent to the subsense line 34 and which is stored in the storage section 45 a.Ultimately, the adding section 46 outputs signals obtained by thefollowing operations: Array (2)−Array (1); Array (3)−Array (1); Array(4)−Array (1); Array (5)−Array (1); Array (6)−Array (1); Array (7)−Array(1); and Array (8)−Array (1). Namely, each signal outputted by theadding section 46 is such a signal from which the noise signal(corresponding to the signal of Array (1)) included in the sense lines33 has been removed. Furthermore, the subtracting section 41 hasperformed the difference signal operation between the sense lines 33adjacent to each other. This allows the adding section 46 to output thesignals from which the noise signals have been more reliably removed.

(2) Noise Processing Performed by Touch Panel System 1 b

With reference to FIGS. 7 and 8, the following will describe noiseprocessing performed by the touch panel system 1 b. FIG. 8 is a flowchart illustrating a noise canceling process, which is a basic processof the touch panel system 1 b.

Upon activation of the touch panel system 1 b, the drive line 35 issupplied with an electric potential at a certain interval. The user'sperforming a touch operation on the touch panel 3 b increases acapacitance of a specific sense line 33 corresponding to the touchedposition. Namely, the user's performing the touch operation on the touchpanel 3 b increases a value of an output signal supplied from that senseline 33. The touch panel system 1 b outputs, to the touch panelcontroller 4, output signals supplied from the sense lines 33 and thesub sense line 34, while driving the drive lines 35. Thus, while drivingthe drive lines 35, the touch panel system 1 b detects changes in thecapacitances of the sense lines 33 and a change in the capacitance ofthe sub sense line 34, so as to determine the presence or absence of atouch operation and a touched position.

To be more specific, a noise such as a clock generated in the displaydevice 2 and other noises coming from the outside are reflected in thetouch panel 3 b. Therefore, each of the main sensor group 31 a and thesub sensor group 32 a detects various kinds of noise components.Specifically, the output signal supplied from the sense line 33 includesnot only a signal derived from the touch operation itself but also anoise signal (noise component). Meanwhile, the sub sense line 34 isconfigured not to detect a touch operation. Therefore, the output signalsupplied from the sub sense line 34 includes a noise signal (noisecomponent), but does not include a signal derived from the touchoperation (F601).

Next, the switches SW select the lower terminals (F602). Then, thesubtracting section 41 finds a difference (sense line (Sn+1)−sense lineSn: a first difference) between a sense line 33 (sense line Sn) and asense line (sense line Sn+1) which is one of two sense lines 33 adjacentto the certain sense line 33 and is closer to the sub sense line 34 thanthe other is. In this step, a difference (third difference) between thesub sense line 34 and a sense line 33 which is closer to the sub senseline 34 than any other sense lines 33 is found (F603).

For Arrays (1) through (8) shown in FIG. 7, the subtracting section 41performs the following four difference signal operations:

-   -   Array (2)−Array (1) (The resulting difference value is referred        to as “A”.)    -   Array (4)−Array (3) (The resulting difference value is referred        to as “C”.)    -   Array (6)−Array (5) (The resulting difference value is referred        to as “E”.)    -   Array (8)−Array (7) (The resulting difference value is referred        to as “G”.)        Namely, in the step F603, the subtracting section 41 performs        the difference signal operations on Arrays (1) through (8),        which includes the sub sense line 34.

The difference values A, C, E, and G found by the subtracting section 41are stored in the storage sections 45 a through 45 d, respectively.Namely, the storage section 45 a stores the difference value A, thestorage section 45 b stores the difference value C, the storage section45 c stores the difference value E, and the storage section 45 d storesthe difference value G (F604).

Next, the switches SW selecting the lower terminals are turned to select(close) the upper terminals (F605). Then, the subtracting section 41performs an operation similar to that of F603. Specifically, thesubtracting section 41 performs a difference signal operation (senseline Sn−sense line (Sn−1): a second difference) between the sense line33 (sense line Sn) and a sense line (sense line Sn−1) which is one ofthe two sense lines 33 adjacent to the certain sense line 33 and isfurther away from the sub sense line 34 than the other is (F606).

For Arrays (1) through (8) shown in FIG. 7, the subtracting section 41performs the following three difference signal operations:

-   -   Array (3)−Array (2) (The resulting difference value is referred        to as “B”.)    -   Array (5)−Array (4) (The resulting difference value is referred        to as “D”.)    -   Array (7)−Array (6) (The resulting difference value is referred        to as “F”.)        Namely, in the step F606, the subtracting section 41 performs        the difference signal operations on Arrays (2) through (7),        which does not include the sub sense line 34.

Next, the adding section 46 performs an adding operation for adding up(i) the difference values B, D, and F found in the step F606 and (ii)the difference values A, C, E, and G stored in the respective storagesections 45 a through 45 d. Namely, the adding section 46 adds up (i)the difference values (the difference values A, C, E, and G) found whenthe lower terminals are selected by the switches SW and (ii) thedifference values (the difference values B, D, and F) found when theupper terminals are selected by the switches SW (F607).

In the case of Arrays (1) through (8) shown in FIG. 7, the addingsection 46 adds up (i) the difference value A (Array (2)−Array (1)signal) stored in the storage section 45 a and (ii) the difference valueB (Array (3)−Array (2) signal) outputted by the subtracting section 41.This adding operation is expressed as below:

${{{Difference}\mspace{14mu}{value}\mspace{14mu} A} + {{Difference}\mspace{14mu}{value}\mspace{14mu} B}} = {{\left\{ {{{Array}\mspace{14mu}(2)} - {{Array}\mspace{14mu}(1)}} \right\} + \left\{ {{{Array}\mspace{14mu}(3)} - {{Array}\mspace{14mu}(2)}} \right\}} = {{{Array}\mspace{14mu}(3)} - {{Array}\mspace{14mu}(1)\left( {{The}\mspace{14mu}{resulting}\mspace{14mu}{difference}\mspace{14mu}{value}\mspace{14mu}{is}\mspace{14mu}{referred}\mspace{14mu}{to}\mspace{14mu}{{as}\mspace{20mu}}^{``}{difference}\mspace{14mu}{value}\mspace{14mu}{H^{"}.}} \right)}}}$This provides an Array (3)−Array (1) signal. The adding section 46performs such operations sequentially.

Specifically, the adding section 46 adds, to the difference value H(Array (3)−Array (1) signal), the difference value C (Array (4)−Array(3) signal) stored in the storage section 45 b. This provides an Array(4)−Array (1) signal (difference value I).

Next, the adding section 46 adds, to the difference value I (Array(4)−Array (1) signal), the difference value D (Array (5)−Array (4)signal) outputted by the subtracting section 41. This provides an Array(5)−Array (1) signal (difference value J).

Next, the adding section 46 adds, to the difference value J (Array(5)−Array (1) signal), the difference value E (Array (6)−Array (5)signal) stored in the storage section 45 c. This provides an Array(6)−Array (1) signal (difference value K).

Next, the adding section 46 adds, to the difference value K (Array(6)−Array (1) signal), the difference value F (Array (7)−Array (6)signal) outputted by the subtracting section 41. This provides an Array(7)−Array (1) signal (difference value L).

Next, the adding section 46 adds, to the difference value L (Array(7)−Array (1) signal), the difference value G (Array (8)−Array (7)signal) stored in the storage section 45 d. This provides an Array(8)−Array (1) signal (difference value M).

Note that the difference value A (i.e., Array (2)−Array (1) signal)stored in the storage section 45 a is outputted without being subjectedto any adding operation by the adding section 46.

Thus, the adding section 46 outputs the following signals:

-   -   Array (2)−Array (1) signal=Difference value A    -   Array (3)−Array (1) signal=Difference value H    -   Array (4)−Array (1) signal=Difference value I    -   Array (5)−Array (1) signal=Difference value J    -   Array (6)−Array (1) signal=Difference value K    -   Array (7)−Array (1) signal=Difference value L    -   Array (8)−Array (1) signal=Difference value M

In the configuration shown in FIG. 7, Arrays (2) through (8) are thesense lines 33, and Array (1) is the sub sense line 34. As a result ofthe adding operations performed by the adding section 46, the signal ofArray (1) (noise signal) is removed from each of the signals of Arrays(2) through (8). Accordingly, each output signal supplied from theadding section 46 is such a signal from which a noise signal included inthe sense line 33 has been removed. Thus, it is possible to provide asignal value derived from a touch operation itself, which signal valueis generated in response to the touch operation. Each output signal ofthe adding section 46, from which the noise signal has been removed, isoutputted to the coordinates detecting section 42 in the touch panelcontroller 4. Namely, the signals derived from the touch operationitself are outputted to the coordinates detecting section 42 (F608).

As described above, the touch panel system 1 b obtains a differencesignal value between sense lines 33 adjacent to each other. Namely, adifference is found between the adjacent sense lines 33, which have ahigher correlation in terms of noise. Furthermore, from an output signalsupplied from each sense line 33, a signal (noise signal) of the subsense line 34 is removed. Therefore, as compared with the touch panelsystems 1 and 1 a of Embodiments 1 and 2, the touch panel system 1 b canremove a noise more reliably.

In addition, according to the touch panel system 1 b, the adding section46 sequentially performs adding operations from the sub sense line 34side (i.e., in the order of increasing distance between a sense lineinvolved in a certain adding operation and the sub-sense line).Therefore, it is possible to remove a noise by performing the addingoperations in such a manner that a result of an adding operation is usedin a next adding operation.

Embodiment 4

A driving method of a touch panel system of the present invention is notparticularly limited. Preferably, the driving method is an orthogonalsequence driving method. In other words, drive lines 35 are preferablyparallel driven. FIG. 9 is a view illustrating a driving method of atouch panel which driving method is employed in a conventional touchpanel system. FIG. 10 is a view illustrating a driving method(orthogonal sequence driving method) of a touch panel which drivingmethod is employed in a touch panel system of the present invention.

FIG. 9 shows one sense line extracted from the touch panel and providedwith four sensors. As shown in FIG. 9, the conventional touch panelsystem drives drive lines in the following manner: +V volt is applied toa drive line which is to be driven, so that the drive lines are drivensequentially.

Specifically, in the first drive line driving, +V volt is applied to theleftmost sensor. This gives the first Vout measurement result (X1)expressed by:X1=C1×V/Cint

Similarly, in the second drive line driving, +V volt is applied to thesecond sensor from the left. This gives the second Vout measurementresult (X2) expressed by:X2=C2×V/Cint

In the third drive line driving, +V volt is applied to the third sensorfrom the left. This gives the third Vout measurement result (X3)expressed by:X3=C3×V/Cint

In the fourth drive line driving, +V volt is applied to the rightmostsensor. This gives the fourth Vout measurement result (X4) expressed by:X4=C4×V/Cint

FIG. 10 shows, as well as FIG. 9, one sense line extracted from thetouch panel and provided with four sensors. As shown in FIG. 10,according to the orthogonal sequence driving method, drive lines aredriven in such a manner that +V volt or −V volt is applied to all thedrive lines. Namely, according to the orthogonal sequence drivingmethod, the drive lines are parallel driven.

Specifically, in the first drive line driving, +V volt is applied to allthe sensors. This gives the first Vout measurement result (Y1) expressedby:Y1=(C1+C2+C3+C4)×V/Cint

In the second drive line driving, +V volt is applied to the leftmostsensor, −V volt is applied to the second sensor from the left, +V voltis applied to the third sensor from the left, and −V volt is applied tothe rightmost sensor. This gives the second Vout measurement result (Y2)expressed by:Y2=(C1−C2+C3−C4)×V/Cint

In the third drive line driving, +V volt is applied to the leftmostsensor, +V volt is applied to the second sensor from the left, −V voltis applied to the third sensor from the left, and −V volt is applied tothe rightmost sensor. This gives the third Vout measurement result (Y3)expressed by:Y3=(C1+C2−C3−C4)×V/Cint

In the fourth drive line driving, +V volt is applied to the leftmostsensor, −V volt is applied to the second sensor from the left, −V voltis applied to the third sensor from the left, and +V volt is applied tothe rightmost sensor. This gives the fourth Vout measurement result (Y4)expressed by:Y4=(C1−C2−C3+C4)×V/Cint

According to the configuration shown in FIG. 10, capacitance values (C1,C2, C3, C4) can be obtained by an inner product calculation of (i)output sequences (Y1, Y2, Y3, Y4) and (ii) orthogonal codes di. Such theformula is established due to orthogonality of the orthogonal code di.Here, the code di indicates codes of positive and/or negative voltagesapplied to a respective drive line. Specifically, the code dl indicatescodes of voltages applied to the leftmost sensor, and is expressed as“+1, +1, +1, +1”. The code d2 indicates codes of voltages applied to thesecond sensor from the left, and is expressed as “+1, −1, +1, −1”. Thecode d3 indicates codes of voltages applied to the third sensor from theleft, and is expressed as “+1, +1, −1, −1”. The code d4 indicates codesof voltages applied to the rightmost sensor, and is expressed as “+1,−1, −1, +1”.

The values of C1, C2, C3, C4 are found by inner product calculations of(i) the output sequences Y1, Y2, Y3, Y4 and (ii) the codes d1, d2, d3,d4 as follows:

C 1 = 1 × Y 1 + 1 × Y 2 + 1 × Y 3 + 1 × Y 4 = 4C 1 × V/CintC 2 = 1 × Y 1 + (−1) × Y 2 + 1 × Y 3 + (−1) × Y 4 = 4C 2 × V/CintC 3 = 1 × Y 1 + 1 × Y 2 + (−1) × Y 3 + (−1) × Y 4 = 4C 3 × V/CintC 4 = 1 × Y 1 + (−1) × Y 2 + (−1) × Y 3 + (−1) × Y 4 = 4C 3 × V/Cint

Thus, due to the orthogonality of the codes di, Ci are obtained by innerproduct calculation of the codes di and the output sequences Yi. Now,the result thus obtained is compared with the result obtained by theconventional driving method shown in FIG. 9. In a case where theorthogonal sequence driving method and the conventional driving methodperform the same number of driving operations, the orthogonal sequencedriving method allows detection of values four times greater than thoseof the conventional driving method. FIG. 11 is a view illustrating aprocess which needs to be performed by the touch panel of the drivingmethod of FIG. 9 in order that it achieves sensitivity equivalent tothat of the touch panel of the driving method of FIG. 10. As shown inFIG. 11, in order that the driving method of FIG. 9 achieves thesensitivity equivalent to that given by the driving method of FIG. 10,the driving method of FIG. 9 needs to drive a certain drive line fourtimes and to sum the results. Namely, according to the driving method ofFIG. 9, a driving period for the drive lines is four times longer thanthat of the driving method of FIG. 10. Conversely, with a driving periodfor the drive lines which driving period is reduced to one-quarter ofthat of the driving method shown in FIG. 9, the driving method shown inFIG. 10 achieves sensitivity equivalent to that given by theconventional driving method shown in FIG. 9. Thus, according to thedriving method shown in FIG. 10, it is possible to reduce electric powerconsumption of the touch panel system.

FIG. 12 is a view schematically illustrating a touch panel system 1 cincluding a touch panel 3 driven by such the orthogonal sequence drivingmethod. Specifically, the touch panel system 1 c of FIG. 12 is shownwith drive lines and sense lines, which correspond to the generalizedfour drive lines and one sense line of FIG. 10.

Specifically, the touch panel system 1 c includes M drive lines 35, Lsense lines 33 (each of M and L is a natural number), and capacitanceswhich are formed between the drive lines 35 and the sense lines 33 so asto be arranged in a matrix. The touch panel system 1 c performs thefollowing operation: With respect to a matrix Cij (i=1, . . . , M, j=1,. . . , L) of these capacitances, the code di=(di1, . . . , diN) (i=1, .. . , M) is used, which is constituted by “+1” and “−1” being orthogonalto each other and each having a code length N. Consequently, all the Mdrive lines 35 are driven concurrently in parallel, while applying +Vvolt in a case of “+1” and applying −V volt in a case of “−1”. Further,capacitance values Cij are estimated by inner product calculation“di·sj=Σ(k=1, . . . , N)dik·sjk”, i.e., inner product calculation of (i)output sequences sj=(sj1, . . . , sjN) (j=1, . . . , L) read fromrespective sense lines 33 and (ii) the codes di. In order to performsuch the inner product calculation, the touch panel system 1 c includesan electric charge integrator (calculation section) 47. A strength of anoutput signal (Vout) supplied from the electric charge integrator 47 isfound by:Vout=Cf×Vdrive×N/Cint

The output sequence sj is expressed as follows:

$\begin{matrix}{{sj} = \left( {{{sj}\; 1},\ldots\mspace{11mu},{sjN}} \right)} \\{= \left( {{{\Sigma\left( {{k = 1},\ldots\mspace{14mu},M} \right)}{Ckj} \times {dk}\; 1},\ldots\mspace{11mu},{{\Sigma\left( {{k = 1},\ldots\mspace{14mu},M} \right)}{Ckj} \times}} \right.} \\{\left. {dkN} \right) \times \left( {V\;{drive}\text{/}{Cint}} \right)} \\{= \left( {{\Sigma\left( {{k = 1},\ldots\mspace{14mu},M} \right)}{Ckj} \times \left( {{{dk}\; 1},\ldots\mspace{11mu},{dkN}} \right) \times \left( {{Vdrive}\text{/}{Cint}} \right)} \right.} \\{= {{\Sigma\left( {{k = 1},\ldots\mspace{14mu},M} \right)}\left( {{Ckj} \times {dk}} \right) \times \left( {V\;{drive}\text{/}{Cint}} \right)}}\end{matrix}$

The inner product of the code di and the output sequence sj is expressedas follows:

$\begin{matrix}{{{di} \cdot {sj}} = {{di} \cdot \left( {{\Sigma\left( {{k = 1},\ldots\mspace{11mu},M} \right)}\left( {{Ckj} \times {dk}} \right) \times \left( {{Vdrive}\text{/}{Cint}} \right)} \right)}} \\{= {{\Sigma\left( {{k = 1},\ldots\mspace{14mu},M} \right)}\left( {{Ckj} \times {{di} \cdot {dk}}} \right) \times \left( {{Vdrive}\text{/}{Cint}} \right)}} \\{= {{\Sigma\left( {{k = 1},\ldots\mspace{11mu},M} \right)}\left( {{Ckj} \times N \times \delta\;{ik}} \right) \times \left( {{Vdrive}\text{/}{Cint}} \right)}} \\{\left\lbrack {{{\delta\;{ik}} = {{1\mspace{14mu}{if}\mspace{14mu} i} = k}},{0\mspace{14mu}{if}\mspace{14mu}{else}}} \right\rbrack} \\{= {{Cij} \times N \times \left( {{Vdrive}\text{/}{Cint}} \right)}}\end{matrix}$

Thus, according to the touch panel system 1 c, the touch panel 3 isdriven by the orthogonal sequence driving method. Therefore, thefollowing generalization is possible: By finding an inner product of thecode di and the output sequence sj, a signal of the capacitance Cij ismultiplied by N (code length). This driving method provides an effectthat a signal strength of a capacitance is N-folded, regardless of thenumber of drive lines 35 (i.e., “M”). Conversely, by employing theorthogonal sequence driving method, sensitivity equivalent to that givenby the conventional driving method shown in FIG. 9 can be achieved witha driving period for the drive lines which period is reduced to one-Nthof that of the driving method shown in FIG. 9. Namely, employing theorthogonal sequence driving method can reduce the number of times thatthe drive lines should be driven. This makes it possible to reduceelectric power consumption of the touch panel system 1 c.

Embodiment 5

FIG. 13 is a view schematically illustrating a basic configuration of atouch panel system 1 d according to the present embodiment. The touchpanel system 1 d is configured by employing, in the touch panel system 1b with the noise canceling function shown in FIG. 7, the orthogonalsequence driving method for the drive lines 35 which is shown in FIGS.10 and 12 and which is employed in the touch panel system 1 c. Since thetouch panel system 1 d operates in the same manner as theabove-described touch panel systems 1 b and 1 c, explanations thereofare omitted here.

According to the touch panel system 1 d, a difference signal value isfound between sense lines 33 which are adjacent to each other. Namely, adifference is found between the adjacent sense lines 33, which have ahigher correlation in terms of noise. Furthermore, from an output signalsupplied from each sense line 33, a signal (noise signal) of a sub senseline 34 is removed. Therefore, as compared with the touch panel systems1 and 1 a of Embodiments 1 and 2, the touch panel system 1 d can removea noise more reliably. Moreover, a signal of a capacitance Cij ismultiplied by N (code length). This allows a capacitance to have anN-folded signal strength, regardless of the number of drive lines 35. Inaddition, since the orthogonal sequence driving method is employed,sensitivity equivalent to that given by the conventional driving methodshown in FIG. 9 can be achieved with a driving period for the drivelines which period is reduced to one-Nth of that of the driving methodshown in FIG. 9. Namely, employing the orthogonal sequence drivingmethod can reduce the number of times that the drive lines should bedriven. This makes it possible to reduce electric power consumption ofthe touch panel system 1 d.

Embodiment 6

FIG. 14 is a view schematically illustrating a basic configuration of atouch panel system 1 e according to the present embodiment. The touchpanel system 1 e includes a subtracting section 41 having a differentconfiguration.

Each of output signals supplied from a sense line 33 and a sub senseline 34 of a touch panel 3 b is an analog signal. Therefore, thesubtracting section 41 includes an analog-to-digital converting section(first analog-to-digital converting section) 48 and a digital subtractor(not illustrated).

With this configuration, output signals (analog signals) supplied fromthe touch panel 3 b are converted into digital signals by theanalog-to-digital converting section 48 of the subtracting section 41.The digital subtractor performs, by use of the digital signals thusconverted, subtracting operations in the same manner as in the touchpanel system 1 b shown in FIG. 7.

Thus, the touch panel system 1 e can remove a noise by (i) converting,into digital signals, analog signals outputted by the touch panel 3 band thereafter (ii) performing subtracting operations.

Embodiment 7

FIG. 15 is a view schematically illustrating a basic configuration of atouch panel system if according to the present embodiment. The touchpanel system if includes a subtracting section 41 having a differentconfiguration.

Output signals supplied from a sense line 33 and a sub sense line 34 ofa touch panel 3 b are analog signals. Therefore, the subtracting section41 includes a differential amplifier 49 and an analog-to-digitalconverting section 48.

With this configuration, in the same manner as in the touch panel system1 b shown in FIG. 7, the differential amplifier 49 performs subtractingoperations on output signals (analog signals) supplied from the touchpanel 3 b, without converting the analog signals into digital signals.The analog-to-digital converting section 48 (second analog-to-digitalconverting section) converts, into a digital signal, an analog signalthus obtained by the subtracting operations.

Thus, the touch panel system 1 f can remove a noise by (i) performingsubtracting operations on analog signals outputted by the touch panel 3b, without converting the analog signals into digital signals, andthereafter (ii) converting the resulting signal into a digital signal.

Embodiment 8

FIG. 16 is a view schematically illustrating a basic configuration of atouch panel system 1 g according to the present embodiment. The touchpanel system 1 g includes a subtracting section 41 having a differentconfiguration. The touch panel system 1 g includes a total differentialamplifier 50 instead of the differential amplifier 49 in the touch panelsystem 1 f shown in FIG. 15.

Output signals supplied from sense lines 33 and a sub sense line 34 of atouch panel 3 b are analog signals. Therefore, the subtracting section41 includes a total differential amplifier 50 and an analog-to-digitalconverting section 48.

With this configuration, in the same manner as in the touch panel system1 b shown in FIG. 7, the total differential amplifier 50 performssubtracting operations on output signals (analog signals) supplied fromthe touch panel 3 b, without converting the analog signals into digitalsignals. The analog-to-digital converting section 48 converts, into adigital signal, an analog signal thus obtained by the subtractingoperations.

FIG. 17 is a circuit diagram illustrating one example of the totaldifferential amplifier 50. The total differential amplifier 50 includestwo pairs each including a capacitance and a switch, the two pairs beingarranged so as to be symmetric to each other with respect to adifferential amplifier. Specifically, a non-inverting input terminal (+)and an inverting input terminal (−) of the differential amplifier aresupplied with signals from sense lines 33 which are adjacent to eachother. A capacitance (feedback capacitance) is provided between aninverting output terminal (−) and the non-inverting input terminal (+)of the differential amplifier so that the capacitance is connected withthe inverting output terminal (−) and the non-inverting input terminal(+), and another capacitance (feedback capacitance) is provided betweena non-inverting output terminal (+) and the inverting input terminal (−)of the differential amplifier so that said another capacitance isconnected with the non-inverting output terminal (+) and the invertinginput terminal (−), these capacitances having the same capacitancevalue. Furthermore, a switch is provided between the inverting outputterminal (−) and the non-inverting input terminal (+) so that the switchis connected with the inverting output terminal (−) and thenon-inverting input terminal (+), and another switch is provided betweenthe non-inverting output terminal (+) and the inverting input terminal(−) so that said another switch is connected with the non-invertingoutput terminal (+) and the inverting input terminal (−).

Thus, the touch panel system 1 g can remove a noise by (i) performingsubtracting operations on analog signals outputted by the touch panel 3b, without converting the analog signals into digital signals, andthereafter (ii) converting the resulting signal into a digital signal.

Embodiment 9

FIG. 18 is a view schematically illustrating a basic configuration of atouch panel system 1 h according to the present embodiment. The touchpanel system 1 h includes (i) a subtracting section 41 having adifferent configuration and involves (i) a different driving method of atouch panel 3 b. The touch panel system 1 h includes a totaldifferential amplifier 50 instead of the differential amplifier 49 inthe touch panel system if shown in FIG. 15.

Output signals supplied from sense lines 33 and a sub sense line 34 ofthe touch panel 3 b are analog signals. Therefore, the subtractingsection 41 includes a total differential amplifier 50 and ananalog-to-digital converting section 48.

With this configuration, in the same manner as in the touch panel system1 b shown in FIG. 7, the total differential amplifier 50 performssubtracting operations on output signals (analog signals) supplied fromthe touch panel 3 b, without converting the analog signals into digitalsignals. The analog-to-digital converting section 48 converts, into adigital signal, an analog signal thus obtained by the subtractingoperations.

Further, the touch panel system 1 h employs, as a driving method for thetouch panel 3 b, the orthogonal sequence driving method shown in FIGS.10, 12, and 13. According to this configuration, as shown in FIG. 10, avoltage for driving four drive lines is applied as follows: In thesecond driving through the fourth driving, +V is applied twice and −V isalso applied twice, i.e., the number of times of application of +V isequal to that of −V. On the other hand, in the first driving, +V isapplied four times. Accordingly, an output value of an output sequenceY1 of the first driving is greater than that of each of output sequencesY2 through Y4 of the second driving through the fourth driving.Therefore, applying a dynamic range to the output value of any of theoutput sequences Y2 through Y4 of the second driving through the fourthdriving causes saturation of the output sequence Y1 of the firstdriving.

In order to address this, the subtracting section 41 of the touch panelsystem 1 h includes the total differential amplifier 50. Further,employed as the total differential amplifier 50 is the one whose inputcommon-mode voltage range is rail to rail. Namely, the totaldifferential amplifier 50 has a wide common-mode input range.Consequently, the total differential amplifier 50 can operate in avoltage range from a power source voltage (Vdd) to GND. Furthermore, adifference between input signals supplied to the total differentialamplifier 50 is amplified. Therefore, regardless of the type of theorthogonal sequence driving method employed in the touch panel 3 b whichis combined with the touch panel system 1 h, an output signal from thetotal differential amplifier 50 is free from the problem of outputsaturation. Note that one example of the total differential amplifier 50is as previously described with reference to FIG. 17.

Thus, the touch panel system 1 h can remove a noise by (i) performingsubtracting operations on analog signals outputted by the touch panel 3b, without converting the analog signals into digital signals, andthereafter (ii) converting the resulting signal into a digital signal.Furthermore, since the touch panel system 1 h includes the totaldifferential amplifier 50 capable of rail-to-rail operation, an outputsignal from the total differential amplifier 50 is free from the problemof output saturation.

Embodiment 10

In Embodiments 1 through 9, a touch panel system provided with a subsensor 32 (sub sense line 34) has been described. However, for a touchpanel system of the present invention, the sub sensor 32 is notessential. In the present embodiment, a touch panel system not providedwith a sub sensor 32 will be described.

FIG. 20 is a view schematically illustrating a basic configuration of atouch panel system 1 i of the present embodiment. The touch panel system1 i includes a subtracting section 41 a for finding a difference signalof sense lines 33 adjacent to each other.

More specifically, a touch panel 3 c includes a plurality of (in FIG.20, five) drive lines 35 and a plurality of (in FIG. 20, eight) senselines 33 intersecting the drive lines 35. The sense lines 33 and thedrive lines 35 are isolated from each other, and the sense lines 33 andthe drive lines 35 are coupled to each other via capacitances.

A touch panel controller 4 includes switches SW, the subtracting section41 a, storage sections 45 a through 45 d, which are arranged in thisorder from an input-receiving side of the touch panel controller 4. Notethat the touch panel controller 4 also includes a coordinates detectingsection 42 (not illustrated) and a CPU 43 (not illustrated) (see FIG.1).

The subtracting section 41 a includes input terminals (input terminalsfor outputs of main sensors) for receiving signals outputted by mainsensors 31. The subtracting section 41 a receives the signals from themain sensors 31. Then, the subtracting section 41 a subtracts one ofadjacent sense lines 33 from the other of the adjacent sense lines 33,so as to find a difference value (difference signal). The signal thusobtained as a result of the subtracting operation by the subtractingsection 41 a is outputted to the coordinates detecting section 42 (seeFIG. 1).

Thus, the touch panel system 1 i differs from the touch panel systems ofthe above-described embodiments in terms of that the touch panel system1 i is not provided with a sub sensor 32 (sub sense line 34) and thesubtracting section 41 a performs a different operation.

The switches SW select, from signals supplied from the sense lines 33,signals to be supplied to the subtracting section 41 a. Morespecifically, each of the switches SW includes two terminals (upper andlower terminals), and selects one of the upper and lower terminals. FIG.20 shows a state where the switches SW select the lower terminals.

The subtracting section 41 a performs difference signal operations on,out of signals supplied from Arrays (1) through (8), signals selected bythe switches SW. Specifically, the subtracting section 41 a performs adifference signal operation between sense lines 33 which are adjacent toeach other. For example, in a case where the switches SW select thelower terminals as shown in FIG. 20, the subtracting section 41 aperforms the following signal operations: Array (8)−Array (7); Array(6)−Array (5); Array (4)−Array (3); and Array (2)−Array (1). On theother hand, in a case where the switches SW select the upper terminals(not illustrated), the subtracting section 41 a performs the followingdifference signal operations: Array (7)−Array (6); Array (5)−Array (4);and Array (3)−Array (2).

In a case where each of the switches SW selects one of the upper andlower terminals, the storage sections 45 a through 45 d store signals(difference operation signals) obtained by the difference operationsperformed by the subtracting section 41 a. On the other hand, in a casewhere each of the switches SW selects the other one of the upper andlower terminals, difference operation signals are directly outputted,not via the storage sections 45 a through 45 d.

(2) Noise Processing Performed by Touch Panel System 1 i

With reference to FIGS. 20 and 21, the following will describe noiseprocessing performed by the touch panel system 1 i. FIG. 21 is a flowchart illustrating a noise canceling process, which is a basic processof the touch panel system 1 i.

Upon activation of the touch panel system 1 i, the drive line 35 issupplied with an electric potential at a certain interval. The user'sperforming a touch operation on the touch panel 3 c changes acapacitance of a specific sense line 33 corresponding to the touchedposition. Namely, the user's performing the touch operation on the touchpanel 3 c changes a value of an output signal supplied from that senseline 33. The touch panel system 1 i outputs, to the touch panelcontroller 4, output signals from the sense lines 33, while driving thedrive lines 35. Thus, while driving the drive lines 35, the touch panelsystem 1 i detects a change in the capacitance of the sense line 33, soas to determine the presence or absence of a touch operation and atouched position.

To be more specific, a noise such as a clock generated in the displaydevice 2 and other noises coming from the outside are reflected in thetouch panel 3 c. Therefore, a main sensor group 31 b detects variouskinds of noise components. Specifically, the output signal supplied fromthe sense line 33 includes not only a signal derived from the touchoperation itself but also a noise signal (noise component) (F701).

Next, the switches SW select the lower terminals (F702). Then, thesubtracting section 41 a finds a difference (sense line (Sn+1)−senseline Sn: a first difference) between a sense line 33 (sense line Sn) anda sense line (sense line Sn+1) which is one of two sense lines 33adjacent to the certain sense line 33 (F703).

For Arrays (1) through (8) shown in FIG. 20, the subtracting section 41a performs the following four difference signal operations:

-   -   Array (2)−Array (1) (The resulting difference value is referred        to as “A”.)    -   Array (4)−Array (3) (The resulting difference value is referred        to as “C”.)    -   Array (6)−Array (5) (The resulting difference value is referred        to as “E”.)    -   Array (8)−Array (7) (The resulting difference value is referred        to as “G”.)

Namely, in the step F703, the subtracting section 41 a performs thedifference signal operations on Arrays (1) through (8) of the senselines 33.

The difference values A, C, E, and G found by the subtracting section 41a are stored in the storage sections 45 a through 45 d, respectively.Namely, the storage section 45 a stores the difference value A, thestorage section 45 b stores the difference value C, the storage section45 c stores the difference value E, and the storage section 45 d storesthe difference value G (F704).

Next, the switches SW selecting the lower terminals are turned to select(close) the upper terminals (F705). Then, the subtracting section 41 aperforms an operation similar to that of F703. Specifically, thesubtracting section 41 a performs a difference signal operation (senseline Sn−(Sn−1): a second difference) between the sense line 33 (senseline Sn) and a sense line (sense line Sn−1) which is the other one ofthe two sense lines 33 adjacent to the certain sense line 33 (F706).

For Arrays (1) through (8) shown in FIG. 20, the subtracting section 41a performs the following three difference signal operations:

-   -   Array (3)−Array (2) (The resulting difference value is referred        to as “B”.)    -   Array (5)−Array (4) (The resulting difference value is referred        to as “D”.)    -   Array (7)−Array (6) (The resulting difference value is referred        to as “F”.)

Namely, in the step F706, the subtracting section 41 a performs thedifference signal operations on Arrays (2) through (7).

As described above, the touch panel system 1 i obtains a differencesignal value between sense lines 33 adjacent to each other. Namely, adifference is found between the adjacent sense lines 33, which have ahigher correlation in terms of noise. This removes the noise componentfrom the output signal supplied from the main sensor group 31 b, therebyextracting the signal derived from the touch operation itself. Thismakes it possible to reliably remove (cancel) a wide variety of noisesreflected in the touch panel 3

Embodiment 11

FIG. 22 is a view schematically illustrating a basic configuration of atouch panel system 1 j of the present embodiment. The touch panel system1 j is configured by employing, in the above-described touch panelsystem 1 i having the noise canceling function shown in FIG. 20, a driveline driving circuit (not illustrated) for parallel driving the drivelines 35. Further, the touch panel system 1 j includes (i) a decodingsection 58 for decoding difference values of capacitances whichdifference values are found by a subtracting section 41 a, (ii) anon-touch operation information storage section 61 for storing adistribution of differences between the capacitances which differencesare decoded by the decoding section 58 when no touch operation isperformed, and (iii) a calibration section 62 for calibrating adistribution of differences between the capacitances which differencesare decoded by the decoding section 58 when a touch operation isperformed. Since the touch panel system 1 j operates in the same manneras the above-described touch panel system 1 i, explanations thereof areomitted here. The following descriptions focus on processes performed bythe subtracting section 41 a, the decoding section 58, the non-touchoperation information storage section 61, and the calibration section62. Further, the following descriptions deal with an example whereorthogonal sequences or M sequences are used as code sequences forparallel driving.

Concretely, assume that code sequences (a component is 1 or −1) forparallel driving the first drive line through the Mth drive line are asfollows:

$\begin{matrix}{d_{1} = \left( {d_{11},d_{12},\ldots\mspace{14mu},d_{1N}} \right)} \\{d_{2} = \left( {d_{21},d_{22},\ldots\mspace{14mu},d_{2N}} \right)} \\\vdots \\{d_{M} = \left( {d_{M\; 1},d_{M\; 2},\ldots\mspace{11mu},d_{MN}} \right)}\end{matrix}$Hereinafter, the code sequences are assumed as orthogonal sequences or Msequences each having a code length N (=2^n−1), having been shifted.Such sequences have a nature of establishing the following formula:

${d_{i} \cdot d_{j}} = {{\sum\limits_{k = 1}^{N}\;{d_{ik} \times d_{jk}}} = {N \times \delta_{ij}}}$

where if d₁ to d_(M) is an orthogonal sequence, δ_(ij)=1 if i=j, 0 ifi≠j,

if d₁ to d_(M) is an M sequence, δ_(ij)=1 if i=j, −1/N if i≠j.

Difference output sequences “S_(j,P) (j=1, . . . , [L/2], P=1, 2) (Lindicates the number of sense lines 33, [n]=an integer part of n)” ofsense lines 33, which difference output sequences correspond to theaforementioned sequences, are defined as follows:

S_(j,1): An output sequence for d₁ through d_(M) when the switches SWselect the lower terminals.

S_(j,2): An output sequence for d₁ through d_(M) when the switches SWselect the upper terminals.

Further, a distribution of differences “(∂sC)_(kj,P) (k=1, . . . , M;j=1, . . . , [L/2]; P=1, 2)” of capacitance values in a direction inwhich each of the drive lines 35 extends (in a direction in which thesense lines 33 are arranged) is defined as follows:(∂sC)_(kj,1) =C _(k,2j) −C _(k,2j−1)(∂sC)_(k,2j) =C _(k,2j+1) −C _(k,2j)

In this case, a difference output of capacitances in the direction inwhich each of the drive lines 35 extends obtained by parallel driving isas follows:

$\begin{matrix}{S_{j,p} = \left( {s_{{j\; 1},p},s_{{j\; 2},p},\ldots\mspace{14mu},s_{{jN},p}} \right)} \\{= \left( {{\sum\limits_{k = 1}^{M}\;{\left( {\partial_{s}C} \right)_{{kj},p} \times d_{k\; 1}}},{\sum\limits_{k = 1}^{N}\;{\left( {\partial_{s}C} \right)_{{kj},p} \times d_{k\; 2}}},\ldots\mspace{14mu},{\sum\limits_{k = 1}^{N}\;{\left( {\partial_{s}C} \right)_{{kj},p} \times}}} \right.} \\{\left. d_{kN} \right) \times \left( {V_{drive}\text{/}C_{INT}} \right)} \\{= {\left( {\sum\limits_{k = 1}^{M}\;{\left( {\partial_{s}C} \right)_{{kj},p} \times \left( {d_{k\; 1},d_{k\; 2},\ldots\mspace{11mu},d_{kN}} \right)}} \right) \times \left( {V_{drive}\text{/}C_{INT}} \right)}} \\{\left. {= {\sum\limits_{k = 1}^{M}\;{\left( {\partial_{s}C} \right)_{{kj},p} \times d_{k}}}} \right) \times \left( {V_{drive}\text{/}C_{INT}} \right)}\end{matrix}$

The decoding section 58 decodes the difference values of thecapacitances which differences value are found by the subtractingsection 41 a (i.e., the distribution of differences between thecapacitance values in the direction in which each of the drive lines 35extends). Specifically, the decoding section 58 finds inner products of(i) the code sequences for parallel driving the drive lines 35 and (ii)the difference output sequences of sense lines 33, which differenceoutput sequences correspond to the aforementioned sequences. Therefore,an inner product value decoded by the decoding section 58 is expressedas follows:

$\begin{matrix}{{d_{i} \cdot s_{j,P}} = {d_{i}{\sum\limits_{k = 1}^{N}\;{\left( {\left( {\partial_{s}C} \right)_{{kj},P} \times d_{k}} \right) \times \left( {V_{drive}\text{/}C_{INT}} \right)}}}} \\{= {\sum\limits_{k = 1}^{N}\;{\left( {\left( {\partial_{s}C} \right)_{{kj},P} \times {d_{i} \cdot d_{k}}} \right) \times \left( {V_{drive}\text{/}C_{INT}} \right)}}} \\{= {\sum\limits_{k = 1}^{N}\;{\left( {\left( {\partial_{s}C} \right)_{{kj},P} \times N \times \delta_{ik}} \right) \times \left( {V_{drive}\text{/}C_{INT}} \right)}}}\end{matrix}$ where${{d_{i} \cdot d_{j}} = {{\sum\limits_{k = 1}^{N}\;{d_{ik} \times d_{jk}}} = {N \times \delta_{ij}}}},$and

if d₁ to d_(M) is an orthogonal sequence, δ_(ij)=1 if i=j, 0 if i≠j

if d₁ to d_(M) is an M sequence, δ_(ij)=1 if i=j, −1/N if i≠j.

Thus, the decoding section 58 finds, as a main component of the decodedinner product value d₁·s_(j,P), an N-folded distribution of differences(∂sC)_(kj,P) between the capacitance values in the direction in whicheach of the drive lines 35 extends. Accordingly, by regarding anestimate value of the distribution of differences (∂sC)_(ij,P) betweenthe capacitance values in the direction in which each of the drive linesextends as the inner product value d_(i)·s_(j,P), it is possible to readsignal strengths of the capacitance values which signal strengths havebeen multiplied by N (i.e., multiplied by a code length).

Meanwhile, as described above, by defining the difference outputsequences S_(j,P) (P=1, 2) of the sense lines 33, a common mode noisesuperimposed in common on sense lines 33 adjacent to each other iscanceled. This makes it possible to read a difference capacitance with ahigh SNR.

As described above, according to the touch panel system 1 j, the touchpanel 3 c is parallel driven, and the decoding section 58 decodes thevalues of the differences between the capacitances which values arefound by the subtracting section 41 a. Consequently, signals of thecapacitances are multiplied by a code length (i.e., multiplied by N).Therefore, signal strengths of the capacitances are increased,regardless of the number of drive lines 35. Further, provided thatnecessary signal strengths are merely equal to those of the conventionaldriving method shown in FIG. 9, it is possible to reduce a drivingperiod for the drive lines 35 to one-Nth of that of the driving methodshown in FIG. 9. Namely, it is possible to reduce the number of timesthat the drive lines 35 should be driven. This makes it possible toreduce electric power consumption of the touch panel system 1 j.

Preferably, the touch panel system 1 j is configured such that thecalibration section 62 subtracts (i) differences between respectivepairs of the sense lines 33 adjacent to each other (=a distribution ofdifference values in the entire touch panel) which differences are foundwhen no touch operation is performed from (ii) differences between therespective pairs of the sense lines 33 adjacent to each other (i.e., adistribution of difference values in the entire touch panel 3 c) whichdifferences are found when a touch operation is performed. Namely, it ispreferable that (i) such the difference signal operation is performedbefore and after a touch operation and (ii) subtraction is performedbetween difference value signals obtained before and after the touchoperation. For example, the non-touch operation information storagesection 61 stores an estimated value of a distribution of differences(∂sC)_(kj,P) found in an initial state where no touch operation isperformed (when no touch operation is performed). Then, the calibrationsection 62 subtracts (i) the estimated value of the distribution of thedifferences (∂sC)_(kj,P) found when no touch operation is performed,which estimated value is stored in the non-touch operation informationstorage section 61, from (ii) an estimated value of a distribution ofdifferences (∂sC)_(kj) found when a touch operation is performed. Thus,the calibration section 62 subtracts (i) the distribution of thedifferences between capacitances found when no touch operation isperformed which distribution is stored in the non-touch operationinformation storage section from (ii) the distribution of differencesbetween the capacitances found when a touch operation is performed(i.e., the difference value signal found when a touch operation isperformed−the difference value signal found when no touch operation isperformed). This makes it possible to cancel an offset inherent in thetouch panel 3 c.

Thus, the touch panel system 1 j is free from a difference componentresulting from a variation in capacitances which variation is inherentin the touch panel 3 c. Consequently, only a difference componentresulting from the touch operation is detected. In the case of the Msequence, an error component (δ_(ij)=−1/N if else i≠j) mixes therein,which does not occur in the case of the orthogonal sequence. However,this error component results only from the touch operation. Therefore,if N is increased (e.g., N=63 or 127), a degree of deterioration of SNRbecomes smaller.

Embodiment 12

FIG. 23 is a view schematically illustrating a basic configuration of atouch panel system 1 k of the present embodiment. The touch panel system1 k includes a subtracting section 41 a having a differentconfiguration.

Output signals supplied from sense lines 33 of a touch panel 3 c areanalog signals. Therefore, the subtracting section 41 a includes ananalog-to-digital converting section (third analog-to-digital convertingsection) 48 a and a digital subtractor (not illustrated).

With this configuration, output signals (analog signals) supplied fromthe touch panel 3 c are converted into digital signals by theanalog-to-digital converting section 48 a of the subtracting section 41a. The digital subtractor performs, by use of the digital signals thusconverted, subtracting operations in the same manner as in the touchpanel systems 1 i and 1 j shown in FIG. 20.

Thus, the touch panel system 1 k can remove a noise by (i) converting,into digital signals, analog signals outputted by the touch panel 3 cand thereafter (ii) performing subtracting operations.

Embodiment 13

FIG. 24 is a view schematically illustrating a basic configuration of atouch panel system 1 m of the present embodiment. The touch panel system1 m includes a subtracting section 41 a having a differentconfiguration.

Output signals supplied from sense lines 33 of a touch panel 3 c areanalog signals. Therefore, the subtracting section 41 a includes adifferential amplifier 49 and an analog-to-digital converting section 48a (fourth analog-to-digital converting section).

With this configuration, in the same manner as in the touch panel system1 i shown in FIG. 20, the differential amplifier 49 performs subtractingoperations on output signals (analog signals) supplied from the touchpanel 3 c, without converting the analog signals into digital signals.The analog-to-digital converting section 48 a converts, into a digitalsignal, an analog signal thus obtained by the subtracting operations.

Thus, the touch panel system 1 m can remove a noise by (i) performingsubtracting operations on analog signals outputted by the touch panel 3c, without converting the analog signals into digital signals, andthereafter (ii) converting the resulting signal into a digital signal.

Embodiment 14

FIG. 25 is a view schematically illustrating a basic configuration of atouch panel system 1 n of the present embodiment. The touch panel system1 n includes a subtracting section 41 a having a differentconfiguration. The touch panel system 1 n includes a total differentialamplifier 50 instead of the differential amplifier 49 in the touch panelsystem 1 m shown in FIG. 24.

Output signals supplied from sense lines 33 of a touch panel 3 c areanalog signals. Therefore, the subtracting section 41 a includes thetotal differential amplifier 50 and an analog-to-digital convertingsection 48 a.

With this configuration, in the same manner as in the touch panel system1 i shown in FIG. 20, the total differential amplifier 50 performssubtracting operations on output signals (analog signals) from the touchpanel 3 c, without converting the analog signals into digital signals.The analog-to-digital converting section 48 a converts, into a digitalsignal, an analog signal thus obtained by the subtracting operations.

Thus, the touch panel system 1 n can remove a noise by (i) performingsubtracting operations on analog signals outputted by the touch panel 3c, without converting the analog signals into digital signals, andthereafter (ii) converting the resulting signal into a digital signal.

Embodiment 15

FIG. 26 is a view schematically illustrating a basic configuration of atouch panel system to of the present embodiment. The touch panel system1 o includes a subtracting section 41 a having a differentconfiguration. The touch panel system 10 includes a total differentialamplifier 50 instead of the differential amplifier 49 in the touch panelsystem 1 m shown in FIG. 26.

Output signals supplied from sense lines 33 of a touch panel 3 c areanalog signals. Therefore, the subtracting section 41 a includes thetotal differential amplifier 50 and an analog-to-digital convertingsection 48 a.

With this configuration, in the same manner as in the touch panel system1 i shown in FIG. 20, the total differential amplifier 50 performssubtracting operations on output signals (analog signals) from the touchpanel 3 c, without converting the analog signals into digital signals.The analog-to-digital converting section 48 a converts, into a digitalsignal, an analog signal thus obtained by the subtracting operations.

Further, the touch panel system 1 o employs, as a driving method for thetouch panel 3 c, the orthogonal sequence driving method shown in FIGS.10, 12, and 22. According to this configuration, as shown in FIG. 10, avoltage for driving four drive lines is applied as follows: In thesecond driving through the fourth driving, +V is applied twice and −V isalso applied twice, i.e., the number of times of application of +V isequal to that of −V. On the other hand, in the first driving, +V isapplied four times. Accordingly, an output value of an output sequenceY1 of the first driving is greater than that of each of output sequencesY2 through Y4 of the second driving through the fourth driving.Therefore, adding a dynamic range to the output values of the outputsequences Y2 through Y4 of the second driving through the fourth drivingcauses saturation of the output sequence Y1 of the first driving.

In order to address this, the subtracting section 41 a of the touchpanel system to includes the total differential amplifier 50.

Further, employed as the total differential amplifier 50 is the onewhose input common-mode voltage range is rail to rail. Namely, the totaldifferential amplifier 50 has a wide common-mode input range.Consequently, the total differential amplifier 50 can operate in avoltage range from a power source voltage (Vdd) to GND. Furthermore, adifference between input signals supplied to the total differentialamplifier 50 is amplified. Therefore, regardless of the type of theorthogonal sequence driving method employed in the touch panel 3 c whichis combined with the touch panel system 1 o, an output signal from thetotal differential amplifier 50 is free from the problem of outputsaturation. Note that one example of the total differential amplifier 50is as previously described with reference to FIG. 17.

Thus, the touch panel system 1 o can remove a noise by (i) performingsubtracting operations on analog signals outputted by the touch panel 3c, without converting the analog signals into digital signals, andthereafter (ii) converting the resulting signal into a digital signal.Furthermore, since the touch panel system to includes the totaldifferential amplifier 50 capable of rail-to-rail operation, an outputsignal from the total differential amplifier 50 is free from the problemof output saturation.

Embodiment 16

Next, the following will describe a method for detecting a touchoperation, which method is employed in the touch panel systems of theabove-described embodiments. The following descriptions deal with, as anexample, the touch panel system 1 j of FIG. 22. However, the touch panelsystems of other embodiments perform the same operation. The touch panelsystem 1 j includes a judging section 59 for determining the presence orabsence of a touch operation based on a comparison of (i) a differencebetween signals of sense lines 33 adjacent to each other whichdifference is found by the subtracting section 41 a and the decodingsection 58, and (ii) positive and negative threshold values. Note thatthe judging section 59 is supplied with (i) a signal (a distribution ofdifferences between capacitances) having been subjected to a calibrationprocess by the calibration section 62 or (ii) a signal (a distributionof differences between capacitances) having not been subjected to acalibration process by the calibration section 62. In the case where thesignal having not been subjected to the calibration process by thecalibration section 62 is inputted to the judging section 59, adistribution of differences between the capacitances which distributionhas been decoded by the decoding section 58 is directly inputted to thejudging section 59. The following will describe the case where thesignal having not been subjected to the calibration process by thecalibration section 62 is inputted to the judging section 59. However,the same operation is performed also in the case where the signal havingbeen subjected to the calibration process is inputted to the judgingsection 59.

FIG. 27 is a flow chart illustrating a basic process of the judgingsection 59 in the touch panel system 1 j shown in FIG. 22. FIG. 28 is aview schematically illustrating a method of recognizing touchinformation in the flow chart shown in FIG. 27.

As shown in FIG. 27, the judging section 59 first obtains values ofdifferences in signal between respective pairs of sense lines adjacentto each other (difference information) “(δsC)_(ij,P)” which values arefound by the subtracting section 41 a and the decoding section 59(F801). Next, the judging section 59 compares the values of thedifferences with a positive threshold value THp and a negative thresholdvalue THm, each of which is stored in the judging section 59, so as tocreate an increase and decrease table (F802). This increase and decreasetable is, for example, a ternary increase and decrease table as shown in(a) of FIG. 28.

Next, the ternary increase and decrease table is converted into a binaryimage (i.e., binarized) (F803). For example, in a case where theincrease and decrease table shown in (a) of FIG. 28 is scanned in theorder from a sense line S1 to a sense line S7 (in a direction toward theright in FIG. 28), the following operation is carried out: In theincrease and decrease table, if the value “+” is scanned, the valuetherein and subsequent value(s) are all converted into “1” until thevalue “−” is scanned next. Meanwhile, if the value “−” is scanned, thescanning is performed in a direction opposite to the scanning direction(in a direction toward the left in FIG. 28) and the value therein issurely converted into “1”. In this manner, binarized data as shown in(b) of FIG. 28 is obtained.

Next, in order to extract touch information from the binarized data, aconnected component is extracted (F804). For example, in (b) of FIG. 28,if the values “1” are arranged side by side on drive lines adjacent toeach other and on a single sense line, (i) a connected componentincluding one of such the values “1” and (ii) a connected componentincluding the other one of such the values “1” are regarded as a singleconnected component, which is set as a candidate of a touched position.Namely, each of the boxed parts including the values “1” in (c) of FIG.28 is regarded as a single connected component, and is extracted as acandidate of a touched position.

Lastly, based on the extracted candidates of the touched position, touchinformation (the size, position, etc. of the touch) is recognized(F805).

Thus, based on a difference between signals of sense lines 33 adjacentto each other from which difference a noise signal has been removed, thejudging section 59 determines the presence or absence of a touchoperation. This makes it possible to accurately determine the presenceor absence of the touch operation.

Furthermore, in the above-described example, based on a comparison of(i) the differences in signals between the respective pairs of senselines 33 adjacent to each other which differences are found by thesubtracting section 41 a and (ii) the positive and negative thresholdvalues (THp, THm), the judging section 59 creates the increase anddecrease table indicating, in ternary, the distribution of thedifferences in signal between the sense lines 33, and converts theincrease and decrease table into the binary image. Namely, thedifferences in signals between the respective pairs of sense lines 33adjacent to each other from which differences the noise signal has beenremoved are inputted to the judging section 59. The judging section 59compares (i) the differences in signals between the respective pairs ofsense lines 33 adjacent to each other and (ii) the positive and negativethreshold values (THp, THm) stored in the judging section 59, so as tocreate the increase and decrease table indicating, in ternary, thedistribution of the differences in signal between the sense lines 33.Further, the judging section 59 binarizes the increase and decreasetable, so that the increase and decrease table is converted into thebinary image. Consequently, from the binary image thus converted, thecandidates of the touched position are extracted. Thus, by recognizingthe touch information (the size, position, etc. of the touch) based onthe binary image, it is possible not only to determine the presence orabsence of the touch operation but also to recognize the touchinformation more accurately.

Embodiment 17

FIG. 29 is a functional block diagram illustrating a configuration of amobile phone 10 including a touch panel system 1. The mobile phone(electronic device) 10 includes a CPU 51, a RAM 53, a ROM 52, a camera54, a microphone 55, a speaker 56, an operation key 57, and the touchpanel system 1. These elements are connected with each other via databus.

The CPU 51 controls operation of the mobile phone 10. The CPU 51executes, for example, a program stored in the ROM 52. The operation key57 receives an instruction entered by a user of the mobile phone 10. TheRAM 53 stores, in a volatile manner, data generated as a result of theCPU 51's executing the program or data inputted via the operation key57. The ROM 52 stores data in an involatile manner.

Further, the ROM 52 is a ROM into which data can be written and fromwhich data can be deleted, for example, an EPROM (Erasable ProgrammableRead-Only Memory) or a flash memory. The mobile phone 10 may beconfigured to include an interface (IF) (not illustrated in FIG. 29)which allows the mobile phone 10 to be connected with another electronicdevice via a wire.

The camera 54 takes an image of a subject in response to the user'soperation on the operation key 57. The obtained image data of thesubject is stored in the RAM 53 or an external memory (e.g., a memorycard). The microphone accepts an inputted voice of the user. The mobilephone 10 binarizes the inputted voice (analog data). Then, the mobilephone 10 transmits the binarized voice to a receiver (e.g., to anothermobile phone). The speaker 56 outputs, for example, sounds based onmusic data stored in the RAM 53.

The touch panel system 1 includes a touch panel 3, a touch panelcontroller 4, a drive line driving circuit 5, and a display device 2.The CPU 51 controls operation of the touch panel system 1. The CPU 51executes, for example, a program stored in the ROM 52. The RAM 53stores, in a volatile manner, data generated as a result of the CPU 51'sexecuting the program. The ROM 52 stores data in an involatile manner.

The display device 2 displays an image stored in the ROM 52 or the RAM53. The display device 2 is stacked on the touch panel 3 or includes thetouch panel 3.

The touch panel system of each of the embodiments as has been describedcan further include a capacitive touch sensor panel 3 d described below.

An embodiment for a capacitive touch sensor panel 3 d of the presentinvention is described below with reference to FIGS. 30 through 52.

Embodiment 18

The description below deals first with an overall arrangement of a touchpanel system 1 p including the capacitive touch sensor panel 3 d, andthen with an arrangement of the touch sensor panel 3 d itself.

(Overall Arrangement of Touch Panel System 1 p)

FIG. 30 is a block diagram illustrating a configuration of the touchpanel system 1 p of Embodiment 18. The touch panel system 1 p includes atouch panel 3 d and a capacitance value distribution detecting circuit22. The touch panel 3 d includes: a plurality of horizontal electrodes 7(see FIGS. 31 and 33) extending parallel to one another in thehorizontal direction; a plurality of vertical electrodes 6 (see FIGS. 31and 32) extending parallel to one another in the vertical direction; andcapacitances formed at respective intersections of the horizontalelectrodes 7 with the vertical electrodes 6.

The horizontal electrodes 7 are connected to respective address linesHL1 to HLM, whereas the vertical electrodes 6 are connected torespective address lines VL1 to VLM.

The capacitance value distribution detecting circuit 22 includes adriver 16. The driver 16 applies voltages to the respective horizontalelectrodes 7 through the respective address lines HL1 to HLM on thebasis of a code sequence to drive the individual capacitances. Thecapacitance value distribution detecting circuit 22 further includes asense amplifier 17. The sense amplifier 17 reads out, through therespective vertical electrodes 6 and the respective address lines VL1 toVLM, linear sums of electric charge corresponding to the individualcapacitances driven by the driver 16, and supplies the linear sums to anAD converter 19. The AD converter 19 carries out an AD conversion of thelinear sums, having been read out through the respective address linesVL1 to VLM, of electric charge corresponding to the individualcapacitances, and supplies a resulting signal to a capacitancedistribution calculating section 20.

The present embodiment of the present invention describes an example of(i) applying voltages to the respective horizontal electrodes to drivethem and (ii) reading out voltage signals from the respective verticalelectrodes. The present invention is, however, not limited to such anarrangement. The present embodiment may alternatively be arranged to (i)apply voltages to the respective vertical electrodes to drive them and(ii) read out voltage signals from the respective horizontal electrodes.

The capacitance distribution calculating section 20 calculates acapacitance distribution over the touch panel 3 d on the basis of (i)the linear sums, having been supplied from the AD converter 19, ofelectric charge corresponding to the individual capacitances and (ii)the code sequence, and thus supplies a result of the calculation to atouch recognizing section 21. The touch recognizing section 21, on thebasis of the capacitance distribution supplied from the capacitancedistribution calculating section 20, recognizes the position on asurface of the touch panel 3 d at which position the touch panel hasbeen touched.

The capacitance value distribution detecting circuit 22 further includesa timing generator 18. The timing generator 18 generates (i) a signalthat regulates the operation of the driver 16, (ii) a signal thatregulates the operation of the sense amplifier 17, and (iii) a signalthat regulates the operation of the AD converter 19. The timinggenerator 18 thus supplies such respective signals to the driver 16, thesense amplifier 17, and the AD converter 19.

(Configuration of Touch Sensor Panel 3 d)

FIG. 31 is a cross-sectional view illustrating a structure of the touchpanel 3 d, which is included in the touch panel system 1 p. The touchpanel 3 d includes: a substrate 203 (insulator); a plurality of verticalelectrodes 6 provided on a first surface 204 (vertical electrodesurface) of the substrate 203; and a plurality of horizontal electrodes7 provided on a second surface 205 (horizontal electrode surface) of thesubstrate 203.

The substrate 203 is an insulating dielectric substrate. The substrate203 is disposed between the vertical electrodes 6 and the horizontalelectrodes 7 to insulate the vertical electrodes 6 from the horizontalelectrodes 7. The substrate 203 is provided with, on the side of thevertical electrodes 6, a transparent adhesive 13 that covers thevertical electrodes 6. The transparent adhesive 13 is provided with acover film 15 adhered to a surface thereof. The substrate 203 isprovided with, on the side of the horizontal electrodes 7, a transparentadhesive 14 that covers the horizontal electrodes 7. To the transparentadhesive 14 is attached a display 12.

(Arrangement of Vertical Electrodes 6)

(a) of FIG. 32 is a diagram illustrating a first basic shape 8 of avertical electrode 6 included in the touch panel 3 d. (b) of FIG. 32 isa diagram illustrating an arrangement of vertical electrodes 6.

The vertical electrodes 6 are, as mentioned above with reference to FIG.31, provided on the first surface 204 of the substrate 203. Eachvertical electrode 6 includes a sequence of a repeat of first basicshapes 8 each formed of fine wires illustrated in (a) of FIG. 32, thefirst basic shapes 8 being connected to one another in a verticaldirection as illustrated in (b) of FIG. 32. Each first basic shape 8 hasline symmetry with respect to a vertical center line C1, and consistsonly of (i) a fine wire inclined at an oblique angle of 45 degrees and(ii) a fine wire inclined at an angle of negative 45 degrees. Thevertical electrodes 6 are provided on the first surface 204 (see FIG.31) of the substrate 203 and arranged at predetermined intervals (forexample, with a pitch of approximately 7 mm) in the horizontaldirection.

Such inclined fine wires forming each first basic shape 8 do not blockpixels included in a liquid crystal display 12 on which the touch panel3 d is placed This arrangement thus prevents moire from occurring.

(Arrangement of Horizontal Electrodes 7)

(a) of FIG. 33 is a diagram illustrating a second basic shape 9 of ahorizontal electrode 7 included in the touch panel 3 d. (b) of FIG. 33is a diagram illustrating an arrangement of horizontal electrodes 7.

The horizontal electrodes 7 are, as mentioned above with reference toFIG. 31, provided on the second surface 205 of the substrate 203. Eachhorizontal electrode 7 includes a sequence of a repeat of second basicshapes 9 each formed of fine wires illustrated in (a) of FIG. 33, thesecond basic shapes 9 being connected to one another in a horizontaldirection as illustrated in (b) of FIG. 33. Each second basic shape 9has line symmetry with respect to the vertical center line C1, andsimilarly to the first basic shapes 8, consists only of (i) a fine wireinclined at an oblique angle of 45 degrees and (ii) a fine wire inclinedat an angle of negative 45 degrees. The horizontal electrodes 7 areprovided on the second surface 205 (see FIG. 31) of the substrate 203and arranged at predetermined intervals (for example, with a pitch ofapproximately 7 mm) in the vertical direction.

The vertical electrodes 6 and the horizontal electrodes 7 are eachformed by, for example, etching a metal thin film or printing a patternwith an ink including electrically conductive nanoparticles. Suchelectrically conductive nanoparticles include silver, gold, platinum,palladium, copper, carbon, or a mixture of any of the above.

(Arrangement of Grid)

FIG. 34 is a diagram illustrating a uniform grid 210 including theplurality of vertical electrodes 6 and the plurality of horizontalelectrodes 7. The vertical electrodes 6 and the horizontal electrodes 7are so disposed that as viewed in the direction perpendicular to thesubstrate 203 (see FIG. 31), the vertical electrodes 6 include nosegment coincident with the horizontal electrodes 7. The verticalelectrodes 6 and the horizontal electrodes 7 are disposed uniformly toform a grid 210 with no gap. The grid 210 has an outline in arectangular shape.

The basic shapes 8 constituting the vertical electrodes 6 and the basicshapes 9 constituting the horizontal electrodes 7 each have linesymmetry. The vertical electrodes 6 and the horizontal electrodes 7 forma grid 210, which has no gap. This arrangement solves the problem causedin, for example, the conventional arrangement illustrated in FIG. 54,that is, the problem of cross-shaped openings 97 that are not covered bya grid, the openings 97 being visibly recognized, with the result ofdecreased visibility. The conventional arrangement illustrated in FIG.54 poses another problem that the capacitance in a portion surroundingan opening 97 is changed differently from that in a portion away fromthe opening 97. The arrangement of Embodiment 18 illustrated in FIG. 34,which causes no opening, advantageously allows a capacitance to changein a uniform manner over the entire substrate 203.

The arrangement illustrated in FIG. 57 includes: vertical electrodes 71each formed by (i) forming a repeat of basic shapes 74 in the verticaldirection and then (ii) joining, to the repeat of basic shapes 74, abasic shape 75 different from the basic shapes 74; and horizontalelectrodes 72 each formed by (i) forming a repeat of basic shape 76 inthe horizontal direction and then (ii) joining, to the repeat of basicshapes 76, a basic shape 77 different from the basic shapes 76. Thevertical electrodes 71 and the horizontal electrodes 72 are placed ontop of each other to form a grid 73 (see FIG. 58), which has (i) alongits bottom side, a zigzag shape 78 due to the basic shapes 75 and (ii)along its left side, a zigzag shape 79 due to the basic shapes 77. Thesezigzag shapes 78 and 79 problematically make it difficult to (i) easilyjoin, directly to the horizontal electrodes 72 forming the zigzag shape79, respective address lines for driving the horizontal electrodes 72,and (ii) easily join, directly to the vertical electrodes 71 forming thezigzag shape 78, respective address lines for driving the verticalelectrodes 71.

In contrast, the arrangement of Embodiment 18 illustrated in FIG. 34includes a grid 210 having a rectangular outline and no zigzag shape.This arrangement thus makes it possible to (i) easily join, directly tothe horizontal electrodes 7, respective address lines for driving thehorizontal electrodes 7, and (ii) easily join, directly to the verticalelectrodes 6, respective address lines for reading out signals from thevertical electrodes 6.

The arrangement illustrated in (a) of FIG. 59 includes conductive Xsequences 162 each formed by (i) forming, in the vertical direction, arepeat of basic shapes each combining a conductive X pad 163 with aconductive X line 164 and then (ii) joining, to the repeat of basicshapes, conductive X pads 163 a, each of which is a basic shapedifferent from the basic shape combining a conductive X pad 163 with aconductive X line 164. Thus, the conductive X sequences 162 illustratedin (a) of FIG. 59 are not formed of a repeat of basic shapes connectedto one another in the vertical direction, and are thus different inconfiguration from the vertical electrodes 6 of Embodiment 18illustrated in FIG. 32.

The arrangement illustrated in (b) of FIG. 59 includes conductive Ysequences 167 each formed by (i) forming, in the horizontal direction, arepeat of basic shapes each combining a conductive Y pad 168 with aconductive Y line 169 and then (ii) joining, to the repeat of basicshapes, conductive Y pads 168 a, each of which is a basic shapedifferent from the basic shape combining a conductive Y pad 168 with aconductive Y line 169. Thus, the conductive Y sequences 167 illustratedin (b) of FIG. 59 are not formed of a repeat of basic shapes connectedto one another in the horizontal direction, and are thus different inconfiguration from the horizontal electrodes 7 of Embodiment 18illustrated in FIG. 33.

As described above, an embodiment of the present invention includes arepeat of basic shapes connected to one another in the vertical orhorizontal direction. This arrangement facilitates design of a verticalelectrode and a horizontal electrode, and makes it possible to carryout, for example, an automatic creation and an automatic correction ofan electrode. The above arrangement further allows a photolithographicmask for use in production of a touch panel and touch panel products tobe inspected by a repeated image processing. The above arrangement thusalso facilitates the production of a touch panel.

The arrangement illustrated in FIG. 59 also poses the following problem:In the case where the conductive X pads 163 and the conductive Y pads168 are each formed of fine wires extending in oblique directions thatare not parallel to the Y axis or the X axis, it is impossible to form auniform grid since (i) the conductive X lines 164 need to be parallel tothe Y axis, and (ii) the conductive Y lines 169 need to be parallel tothe X axis.

The touch panel 3 d of Embodiment 18 can be produced by either formingvertical electrodes 6 and horizontal electrodes 7 on respective surfacesof a single sheet (substrate 203) as illustrated in FIG. 31, orcombining (i) a sheet on which vertical electrodes 6 are formed with(ii) a sheet on which horizontal electrodes 7 are formed. Either caseinvolves the possibility that due to positioning accuracy or combiningaccuracy, the resulting positional relationship between the verticalelectrodes 6 and the horizontal electrodes 7 is subtly shifted from thepositional relationship disclosed in Embodiment 18. This necessitatesdetermining positioning accuracy or combining accuracy for the touchpanel production in correspondence with a required accuracy of detectinga touch position.

(Variation)

(a) of FIG. 35 is a diagram illustrating a first basic shape 8 a of avertical electrode 6 a included as a variation in the touch panel 3 d.(b) of FIG. 35 is a diagram illustrating an arrangement of verticalelectrodes 6 a according to the variation. Each first basic shape 8 a isso arranged that the wiring path for fine wires in the upper half isconnected to the wiring path for fine wires in the lower half at ajunction Q1 narrowed to the width of a single fine wire. Each firstbasic shape 8 a has line symmetry with respect to a vertical center lineC1.

(a) of FIG. 36 is a diagram illustrating a second basic shape 9 a of ahorizontal electrode 7 a included as a variation in the touch panel 3 d.(b) of FIG. 36 is a diagram illustrating an arrangement of horizontalelectrodes 7 a according to the variation. Each second basic shape 9 ais so arranged that (i) the wiring path for fine wires in a left portionis connected to the wiring path for fine wires in a central portion at ajunction Q2 narrowed to the width of a single fine wire and that (ii)the wiring path for fine wires in the central portion is connected tothe wiring path for fine wires in a right portion at a junction Q3narrowed to the width of a single fine wire. Each second basic shape 9 ahas line symmetry with respect to the vertical center line C1.

FIG. 37 is a diagram illustrating a uniform grid 210 a including thevertical electrodes 6 a as a variation and the horizontal electrodes 7 aas a variation. As in the grid 210 illustrated in FIG. 34, the verticalelectrodes 6 a and the horizontal electrodes 7 a are so disposed that asviewed in the direction perpendicular to the substrate 203 (see FIG.31), the vertical electrodes 6 a include no segment coincident with thehorizontal electrodes 7 a. The vertical electrodes 6 a and thehorizontal electrodes 7 a are disposed uniformly to form a grid 210 awith no gap. The grid 210 a has an outline in a rectangular shape.

The respective arrangements of the vertical electrodes 6 a, thehorizontal electrodes 7 a, and the grid 210 a illustrated in FIGS. 35through 37 achieve advantages similar to those achieved by therespective arrangements of the vertical electrodes 6, the horizontalelectrodes 7, and the grid 210 illustrated in FIGS. 32 through 34.

(a) of FIG. 38 is a diagram illustrating a configuration of a firstbasic shape 8 a of a vertical electrode 6 a as a variation, the firstbasic shape 8 a being filled with a transparent electrode material 23.(b) of FIG. 38 is a diagram illustrating the vertical electrodes 6 a asa variation, the vertical electrodes 6 a being filled with thetransparent electrode material 23. (a) of FIG. 39 is a diagramillustrating a configuration of a second basic shape 9 a of a horizontalelectrode 7 a as a variation, the second basic shape 9 a being filledwith the transparent electrode material 23. (b) of FIG. 39 is a diagramillustrating the horizontal electrodes 7 a as a variation, thehorizontal electrodes 7 a being filled with the transparent electrodematerial 23.

In the case where the vertical electrodes 6 a, each including the firstbasic shapes 8 a, are filled with the transparent electrode material 23to its contour as illustrated in FIG. 38, the vertical electrodes 6 aeach have an even lower resistance value. In the case where thehorizontal electrodes 7 a, each including the second basic shapes 9 a,are filled with the transparent electrode material 23 substantially toits contour as illustrated in FIG. 39, the horizontal electrodes 7 aeach have an even lower resistance value. The transparent electrodematerial 23 can be made of, for example, an ITO film or graphene.

The above arrangement can further reduce the width of the fine wires,and thus reduce visibility of the fine wires. In the case where the finewires each have a width of, for example, 0.5 mm or larger, a viewer,when close to a screen of a display device including the touch panel,visibly recognizes the fine wires.

(a) of FIG. 40 is a diagram illustrating an arrangement of the verticalelectrodes 6 a, as a variation, connected to the respective addresslines VL1 to VLM. (b) of FIG. 40 is a diagram illustrating anarrangement of the horizontal electrodes 7 a, as a variation, connectedto the respective address lines HL1 to HLM. (c) of FIG. 40 is a diagramillustrating a grid 210 a including (i) the vertical electrodes 6 aconnected to the respective address lines VL1 to VLM and (ii) thehorizontal electrodes 7 a connected to the respective address lines HL1to HLM.

The grid 210 a, which includes the vertical electrodes 6 a and thehorizontal electrodes 7 a, has a rectangular outline and no zigzag shapeas in the grid 210. This arrangement thus makes it possible to (i)easily join, directly to the horizontal electrodes 7 a, the respectiveaddress lines HL1 to HLM for driving the horizontal electrodes 7 a, and(ii) easily join, directly to the vertical electrodes 6 a, therespective address lines VL1 to VLM for reading out signals from thevertical electrodes 6 a.

Embodiment 19 Configuration of Vertical Electrodes 6 b

(a) of FIG. 41 is a diagram illustrating a first basic shape 8 b of avertical electrode 6 b included in a touch panel of Embodiment 19. (b)of FIG. 41 is a diagram illustrating a configuration of a verticalelectrode 6 b. The vertical electrodes 6 b are, as mentioned above withreference to FIG. 31, provided on the first surface 204 of the substrate203. Each vertical electrode 6 b includes a sequence of a repeat offirst basic shapes 8 b each formed of fine wires, the first basic shapes8 b being connected to one another in the vertical direction. Each firstbasic shape 8 b has point symmetry with respect to a center point P, andconsists only of (i) a fine wire inclined at an oblique angle of 45degrees and (ii) a fine wire inclined at an angle of negative 45degrees. The vertical electrodes 6 b are provided on the first surface204 (see FIG. 31) of the substrate 203 and arranged at predeterminedintervals (for example, with a pitch of approximately 7 mm) in thehorizontal direction.

(Configuration of Horizontal Electrodes 7 b)

(a) of FIG. 42 is a diagram illustrating a second basic shape 9 b of ahorizontal electrode 7 b included in the touch panel of Embodiment 19.(b) of FIG. 42 is a diagram illustrating a configuration of a horizontalelectrode 7 b. The horizontal electrodes 7 b are, as mentioned abovewith reference to FIG. 31, provided on the second surface 205 of thesubstrate 203. Each horizontal electrode 7 b includes a sequence of arepeat of second basic shapes 9 b each formed of fine wires illustratedin (a) of FIG. 42, the second basic shapes 9 b being connected to oneanother in the horizontal direction. Each second basic shape 9 b haspoint symmetry with respect to the center point P, and similarly to thefirst basic shapes 8 b, consists only of (i) a fine wire inclined at anoblique angle of 45 degrees and (ii) a fine wire inclined at an angle ofnegative 45 degrees. The horizontal electrodes 7 b are provided on thesecond surface 205 (see FIG. 31) of the substrate 203 and arranged atpredetermined intervals (for example, with a pitch of approximately 7mm) in the vertical direction.

Embodiment 20 Configuration of Vertical Electrodes 6 c

(a) of FIG. 43 is a diagram illustrating a first basic shape 8 c of avertical electrode 6 c included in a touch panel of Embodiment 20. (b)of FIG. 43 is a diagram illustrating a configuration of a verticalelectrode 6 c. The vertical electrodes 6 c are provided on the firstsurface 204 of the substrate 203 illustrated in FIG. 31. Each verticalelectrode 6 c includes a sequence of a repeat of first basic shapes 8 ceach formed of fine wires, the first basic shapes 8 b being connected toone another in the vertical direction. Each first basic shape 8 c hasline symmetry with respect to (i) a vertical center line C1 and (ii) ahorizontal center line C2, and consists only of (i) a fine wire inclinedat an oblique angle of 45 degrees and (ii) a fine wire inclined at anangle of negative 45 degrees. The vertical electrodes 6 c are providedon the first surface 203 (see FIG. 31) of the substrate 203 and arrangedat predetermined intervals (for example, with a pitch of approximately 7mm) in the horizontal direction.

(Configuration of Horizontal Electrodes 7 c)

(a) of FIG. 44 is a diagram illustrating a second basic shape 9 c of ahorizontal electrode 7 c included in the touch panel of Embodiment 20.(b) of FIG. 44 is a diagram illustrating a configuration of a horizontalelectrode 7 c. The horizontal electrodes 7 c are provided on the secondsurface 205 of the substrate 203 illustrated in FIG. 31. Each horizontalelectrode 7 c includes a sequence of a repeat of second basic shapes 9 ceach formed of fine wires, the second basic shapes 9 b being connectedto one another in the horizontal direction. Each second basic shape 9 chas line symmetry with respect to (i) the vertical center line C1 and(ii) the horizontal center line C2, and consists only of (i) a fine wireinclined at an oblique angle of 45 degrees and (ii) a fine wire inclinedat an angle of negative 45 degrees. The horizontal electrodes 7 c areprovided on the second surface 205 (see FIG. 31) of the substrate 203and arranged at predetermined intervals (for example, with a pitch ofapproximately 7 mm) in the vertical direction.

(Advantage Achieved by Symmetry of Vertical Electrodes and HorizontalElectrodes)

The conventional arrangement illustrated in FIG. 57 includes verticalelectrodes 71 and horizontal electrodes 72 none of which has center-linesymmetry or center-point symmetry. Thus, a capacitive touch sensorhaving an electrode distribution illustrated in FIG. 57 lacks positionalsymmetry in a capacitance change caused by an object having a smalltouch area. This problematically makes it impossible to carry out asymmetric position correction during a touch-position detection, andthus requires a complicated algorithm for increasing the positiondetection precision. This problem leads to an increase in the amount ofnecessary computation, circuit complexity, and a memory usage amount,and results in an increase in, for example, power consumption and cost.

In contrast, vertical electrodes or horizontal electrodes having linesymmetry or point symmetry allow a similar symmetry to occur in acapacitance change caused by an object, such as a pen, that has a smalltouch area. Utilizing this symmetry in a capacitance change allows asymmetric position correction to be carried out during a touch-positiondetection, and thus increases the position detection precision.

As described above, to solve the problem with the position detectionprecision, an embodiment of the present invention includes anarrangement of diamond shapes each formed by fine lines and havingsymmetry. This arrangement allows a large capacitive touch sensor havinga size of 30 inches or larger to highly precisely carry out a positiondetection involving use of an object, such as a pen, that has a smalltouch area.

Embodiment 21 Arrangement of Vertical Electrodes 6 d

(a) of FIG. 45 is a diagram illustrating a first basic shape 8 d of avertical electrode 6 d included in a touch panel of Embodiment 21. (b)of FIG. 45 is a diagram illustrating a configuration of a verticalelectrode 6 d. The vertical electrodes 6 d each correspond to a verticalelectrode 6 a (see FIG. 35) except for a grid pitch that is 7/5 timeslarger. Each first basic shape 8 d is so arranged that the wiring pathfor fine wires in the upper half is connected to the wiring path forfine wires in the lower half at a junction Q4 narrowed to the width of asingle fine wire. Each first basic shape 8 d has line symmetry withrespect to a vertical center line C1.

(a) of FIG. 46 is a diagram illustrating a second basic shape 9 d of ahorizontal electrode 7 d included in the touch panel of Embodiment 21.(b) of FIG. 46 is a diagram illustrating a configuration of a horizontalelectrode 7 d. The horizontal electrodes 7 d each correspond to ahorizontal electrode 7 a (see FIG. 36) except for a grid pitch that is7/5 times larger. Each second basic shape 9 d is so arranged that (i)the wiring path for fine wires in a left portion is connected to thewiring path for fine wires in a central portion at a junction Q5narrowed to the width of a single fine wire and that (ii) the wiringpath for fine wires in the central portion is connected to the wiringpath for fine wires in a right portion at a junction Q6 narrowed to thewidth of a single fine wire. Each second basic shape 9 d has linesymmetry with respect to the vertical center line C1.

Embodiment 22 Arrangement of Vertical Electrodes 6 e

(a) of FIG. 47 is a diagram illustrating a first basic shape 8 e of avertical electrode 6 e included in a touch panel of Embodiment 22. (b)of FIG. 47 is a diagram illustrating a configuration of a verticalelectrode 6 e. The vertical electrodes 6 e each include a sequence of arepeat of first basic shapes 8 e each formed of fine wires, the firstbasic shapes 8 e being connected to one another in the verticaldirection. Each first basic shape 8 e has line symmetry with respect toa vertical center line C1.

Each first basic shape 8 e is so arranged that (i) the wiring path forfine wires in the upper half is connected to the wiring path for finewires in the lower half not at a point narrowed to the width of a singlefine wire and that (ii) the fine wires in the upper half are insteadconnected in the vertical direction to the fine wires in the lower halfat two or more points along any horizontal line.

(Arrangement of Horizontal Electrodes 7 e)

(a) of FIG. 48 is a diagram illustrating a second basic shape 9 e of ahorizontal electrode 7 e included in the touch panel of Embodiment 22.(b) of FIG. 48 is a diagram illustrating a configuration of a horizontalelectrode 7 e. The horizontal electrodes 7 e each include a sequence ofa repeat of second basic shapes 9 e each formed of fine wires, thesecond basic shapes 9 e being connected to one another in the horizontaldirection. Each second basic shape 9 e has line symmetry with respect tothe vertical center line C1.

Each second basic shape 9 e is so arranged that (i) the wiring path forfine wires in a left portion is connected to the wiring path for finewires in a right portion not at a point narrowed to the width of asingle fine wire and that (ii) the fine wires in the left portion areinstead connected in the horizontal direction to the fine wires in theright portion at two or more points along any vertical line.

(Configuration of Grid 210 e)

FIG. 49 is a diagram illustrating a uniform grid 210 e including thevertical electrodes 6 e and the horizontal electrodes 7 e. The verticalelectrodes 6 e and the horizontal electrodes 7 e are so disposed that asviewed in the direction perpendicular to the substrate 203 (see FIG.31), the vertical electrodes 6 e include no segment coincident with thehorizontal electrodes 7 e. The vertical electrodes 6 e and thehorizontal electrodes 7 e are disposed uniformly to form a grid 210 ewith no gap. The grid 210 e has an outline in a rectangular shape.

(Arrangement of Vertical Electrodes 6 f)

(a) of FIG. 50 is a diagram illustrating a first basic shape 8 f ofanother vertical electrode 6 f included in the touch panel of Embodiment22. (b) of FIG. 50 is a diagram illustrating a configuration of suchanother vertical electrode 6 f. The vertical electrodes 6 f each includea sequence of a repeat of first basic shapes 8 f each formed of finewires, the first basic shapes 8 f being connected to one another in thevertical direction. Each first basic shape 8 f has line symmetry withrespect to a vertical center line C1.

As in the basic shapes 8 e, each first basic shape 8 f is so arrangedthat (i) the wiring path for fine wires in the upper half is connectedto the wiring path for fine wires in the lower half not at a pointnarrowed to the width of a single fine wire and that (ii) the fine wiresin the upper half are instead connected in the vertical direction to thefine wires in the lower half at two or more points along any horizontalline.

(Arrangement of Horizontal Electrodes 7 f)

(a) of FIG. 51 is a diagram illustrating a second basic shape 9 f ofanother horizontal electrode 7 f included in the touch panel ofEmbodiment 22. (b) of FIG. 51 is a diagram illustrating a configurationof such another horizontal electrode 7 f. The horizontal electrodes 7 feach include a sequence of a repeat of second basic shapes 9 f eachformed of fine wires, the second basic shapes 9 f being connected to oneanother in the horizontal direction. Each second basic shape 9 f hasline symmetry with respect to the vertical center line C1.

As in the basic shapes 9 e, each second basic shape 9 f is so arrangedthat (i) the wiring path for fine wires in a left portion is connectedto the wiring path for fine wires in a right portion not at a pointnarrowed to the width of a single fine wire and that (ii) the fine wiresin the left portion are instead connected in the horizontal direction tothe fine wires in the right portion at two or more points along anyvertical line.

The arrangement illustrated in FIG. 57 poses another inherent problem:The vertical electrodes 71 of (a) of FIG. 57 and the horizontalelectrodes 72 of (b) of FIG. 57 each have a point at which a wiring pathis connected to another, the point being narrowed to the width of asingle fine wire. If a fine wire is broken at such a point, narrowed tothe width of a single fine wire, during production of a touch sensorpanel, electric current is prevented from flowing through any of theconnected electrodes. Thus, production involving the possibility of abroken fine wire problematically decreases the yield of the touch sensorpanel.

In contrast, an embodiment of the present invention is so arranged that(i) none of the first basic shapes 8 e and 8 f and the second basicshapes 9 e and 9 f includes a point at which a wiring path is connectedto another, the point being narrowed to the width of a single fine wireand that (ii) fine wires are instead connected to each other at two ormore points along any vertical or horizontal line. Thus, even if onefine wire is broken during production, the remaining fine wire maintainsconnection. This arrangement can advantageously prevent disconnection inthe vertical electrodes 6 e and 6 f and the horizontal electrodes 7 eand 7 f.

(Configurations of First Basic Shape 8 g and Second Basic Shape 9 g asVariation)

(a) of FIG. 52 is a diagram illustrating a first basic shape 8 g as avariation. (b) of FIG. 52 is a diagram illustrating a second basic shape9 g as a variation.

Each first basic shape 8 g is so arranged that (i) the wiring path forfine wires in the upper half is connected to the wiring path for finewires in the lower half not at a point narrowed to the width of a singlefine wire and that (ii) the fine wires in the upper half are insteadconnected in the vertical direction to the fine wires in the lower halfat two or more points along any horizontal line. Each first basic shape8 g has point symmetry with respect to a center point P.

Each second basic shape 9 g is so arranged that (i) the wiring path forfine wires in a left portion is connected to the wiring path for finewires in a right portion not at a point narrowed to the width of asingle fine wire and that (ii) the fine wires in the left portion areinstead connected in the horizontal direction to the fine wires in theright portion at two or more points along any vertical line. Each secondbasic shape 9 g has point symmetry with respect to the center point P.

(Configurations of First Basic Shape 8 h and Second Basic Shape 9 h asAnother Variation)

(a) of FIG. 53 is a diagram illustrating a first basic shape 8 h asanother variation. (b) of FIG. 53 is a diagram illustrating a secondbasic shape 9 h as another variation.

Each first basic shape 8 h is so arranged that (i) the wiring path forfine wires in the upper half is connected to the wiring path for finewires in the lower half not at a point narrowed to the width of a singlefine wire and that (ii) the fine wires in the upper half are insteadconnected in the vertical direction to the fine wires in the lower halfat two or more points along any horizontal line. Each first basic shape8 h has line symmetry with respect to a vertical center line C1 and ahorizontal center line C2.

Each second basic shape 9 h is so arranged that (i) the wiring path forfine wires in a left portion is connected to the wiring path for finewires in a right portion not at a point narrowed to the width of asingle fine wire and that (ii) the fine wires in the left portion areinstead connected in the horizontal direction to the fine wires in theright portion at two or more points along any vertical line. Each secondbasic shape 9 h has line symmetry with respect to the vertical centerline C1 and the horizontal center line C2.

Embodiment 23 Configuration of Electronic Blackboard 250

FIG. 54 is a diagram illustrating an appearance of an electronicblackboard 250 (information input-output device) of Embodiment 23. Theelectronic blackboard 250 includes a touch panel system 1 p of anembodiment of the present invention, the touch panel system 1 p in turnincluding a touch panel 3 d of an embodiment of the present invention.The touch panel 3 d is, for example, approximately 80 inches in size.

The present invention can also be expressed as below:

[1] A touch panel system including: a touch panel including a pluralityof sensors; and a touch panel controller for receiving signals from thesensors so as to read data, the plurality of sensors including (i) amain sensor for inputting a signal in response to a touch operationperformed by a user and (ii) a sub sensor provided on a surface of thetouch panel on which surface the main sensor is provided, and the touchpanel controller including subtracting means for (i) receiving a signalsupplied from the main sensor and a signal supplied from the sub sensorand (ii) subtracting, from the signal supplied from the main sensor, thesignal supplied from the sub sensor.

[2] The touch panel system described in [1], wherein the sub sensor isnot touched by the user in the touch operation, and detects a noisegenerated in the sensor.

[3] The touch panel system described in [1] or [2], wherein the mainsensor and the sub sensor are provided so as to be adjacent to eachother.

[4] A touch panel system including: a display device; a touch panelwhich is provided on an upper section or the like of a display screen ofthe display device and which includes a plurality of sensor groupsincluding sensors arranged in a matrix; and a touch panel controller forreceiving signals from the sensor groups so as to read data, the sensorgroups including (i) a main sensor group for inputting a signal inresponse to a touch operation performed by a user and (ii) a sub sensorgroup provided on a surface of the touch panel on which surface the mainsensor group is provided, and the touch panel controller includingsubtracting means for (i) receiving a signal supplied from the mainsensor group and a signal supplied from the sub sensor group and (ii)subtracting, from the signal supplied from the main sensor group, thesignal supplied from the sub sensor group.

[5] The touch panel system described in [4], wherein the sub sensorgroup is not touched by the user in the touch operation, and detects anoise generated in the sensor group.

[6] The touch panel system described in [4] or [5], wherein the mainsensor group and the sub sensor group are provided so as to be adjacentto each other.

[7] The touch panel system described in any of [1] through [6], whereinthe display device is a liquid crystal display, a plasma display, anorganic electroluminescence display, or a field emission display.

[8] An electronic device including a touch panel system described in anyof [1] through [7].

According to each of the above configurations, the touch panel includesthe main sensor section for detecting a touch operation and the subsensor section for detecting a noise, and a difference between a signalof the main sensor section and a signal of the sub sensor section isfound by the subtracting section. This removes a noise signal from theoutput signal which is supplied from the main sensor section, therebyextracting a signal derived from the touch operation itself, whichsignal is generated in response to the touch operation. Therefore, it ispossible to reliably remove (cancel) a wide variety of noises reflectedin the touch panel. Thus, a noise component which is the subject ofremoval is not limited to an AC signal component in a signal includingnoises, but is all noise components reflected in the touch panel.Namely, it is possible to provide a touch panel system and an electronicdevice each of which is capable of canceling basically all noisecomponents.

Also, the present invention can be described as below:

Preferably, the touch panel system of any of the embodiments of thepresent invention is configured such that: the main sensor section isprovided with a plurality of sense lines; the sub sensor section isprovided with a sub sense line extending along a direction in which thesense lines extend; the subtracting section finds a first differencewhich is expressed by (Sn+1)−Sn, the first difference corresponding to adifference between (i) a signal of a sense line Sn which is selectedfrom the plurality of sense lines and (ii) a signal of a sense lineSn+1, which is one of two sense lines adjacent to the sense line Sn, thetwo sense lines being the sense line Sn+1 and a sense line Sn−1 each ofwhich is included in the plurality of sense lines; the subtractingsection finds a second difference which is expressed by Sn−(Sn−1), thesecond difference corresponding to a difference between (i) the signalof the sense line Sn and (ii) a signal of the sense line Sn−1, which isthe other one of the two sense lines; the subtracting section finds athird difference, the third difference corresponding to a differencebetween (i) a signal of the sub sense line and (ii) a signal of a senseline adjacent to the sub sense line which sense line is included in theplurality of sense lines; and the touch panel controller includes anadding section for adding up the first difference, the seconddifference, and the third difference.

According to the above configuration, the subtracting section obtains adifference signal value between sense lines adjacent to each other.Namely, a difference is found between the adjacent sense lines, whichhave a higher correlation in terms of noise. Furthermore, from an outputsignal supplied from each sense line, a signal (noise signal) of the subsense line is removed. This makes it possible to remove a noise morereliably.

The touch panel system of any of the embodiments of the presentinvention may be configured to include: drive lines provided so as tointersect the sense lines and the sub sense line; a drive line drivingcircuit for driving the drive lines in parallel by use of orthogonalsequences or M sequences; capacitances being formed (i) between thesense lines and the drive lines and (ii) between the sub sense line andthe drive lines; and a calculation section for finding capacitancevalues of the respective capacitances by (i) reading output signals fromthe sense lines and the sub sense line and by (ii) finding innerproducts of the output signals and the orthogonal sequences or the Msequences for driving the drive lines in parallel.

According to the above configuration, the touch panel is driven by theorthogonal sequence driving method. Consequently, a signal of thecapacitance is multiplied by a code length (i.e., multiplied by N).Therefore, a signal strength of the capacitance is increased, regardlessof the number of drive lines. Further, provided that a necessary signalstrength is merely equal to that of the conventional method, it ispossible to reduce the number of times that the drive lines should bedriven, thereby enabling to reduce electric power consumption.

The touch panel system of any of the embodiments of the presentinvention may be configured such that: the subtracting section includesa first analog-to-digital converting section for converting, intodigital signals, analog signals supplied from the sense lines and thesub sense line to the subtracting section; and the subtracting sectionuses, in order to find the first difference, the second difference, andthe third difference, the digital signals obtained by the firstanalog-to-digital converting section.

According to the above configuration, it is possible to remove a noiseby (ii) converting, into digital signals, analog signals outputted bythe touch panel, and thereafter by (ii) performing subtractingoperations.

The touch panel system of any of the embodiments of the presentinvention may be configured such that: the subtracting section includesa second analog-to-digital converting section for converting, intodigital signals, analog signals supplied from the sense lines and thesub sense line to the subtracting section; and the secondanalog-to-digital converting section converts, into a digital signal,each of the first difference, the second difference, and the thirddifference that are found by the subtracting section with use of theanalog signals.

According to the above configuration, it is possible to remove a noiseby (i) performing subtracting operations on analog signals outputted bythe touch panel, without converting the analog signals into digitalsignals, and thereafter by (ii) converting the resulting signal into adigital signal.

Preferably, the touch panel system of any of the embodiments of thepresent invention is configured such that: the subtracting sectionincludes a total differential amplifier for finding the firstdifference, the second difference, and the third difference with use ofthe analog signals.

According to the above configuration, it is possible to remove a noiseby (i) causing the total differential amplifier to perform subtractingoperations on analog signals without converting the analog signals intodigital signals which analog signals are outputted by the touch panel,and thereafter by (ii) converting the resulting signal into a digitalsignal.

Preferably, the touch panel system of any of the embodiments of thepresent invention is configured such that: the total differentialamplifier has an input common-mode voltage range which is rail to rail.

The above configuration includes the total differential amplifiercapable of rail-to-rail operation. Therefore, the total differentialamplifier is operable in a voltage range from a power source voltage(Vdd) to GND. Accordingly, an output signal from the total differentialamplifier is free from a problem of output saturation.

Preferably, the touch panel system of any of the embodiments of thepresent invention is configured such that: the adding section adds thefirst difference, the second difference, and the third difference insuch a manner that individual adding operations are carried out in theorder of increasing distance between a sense line involved in a certainadding operation and the sub-sense line, and the adding section uses aresult of one adding operation in a next adding operation.

According to the above configuration, the adding section sequentiallyperforms adding operations in the order of increasing distance between asense line involved in a certain adding operation and the sub-senseline, while utilizing the results of the adding operations. This makesit possible to increase a speed at which an adding operation isperformed.

The touch panel system of any of the embodiments of the presentinvention may be configured such that: the sub sensor section isconfigured not to detect a touch operation performed with respect to thetouch panel.

According to the above configuration, since a signal generated by atouch operation is not detected by the sub sensor section, an outputsignal from the sub sensor section does not include the signal generatedby the touch operation. This prevents a case where the signal valuederived from the touch operation is reduced by the subtracting operationperformed by the subtracting section. Namely, a noise component isremoved without reducing the signal detected by the main sensor section,which signal is generated in response to the touch operation. This makesit possible to further enhance detection sensitivity for a touchoperation.

The touch panel system of any of the embodiments of the presentinvention may be configured such that: the sub sensor section isprovided in a region of the touch panel in which region no touchoperation is performed.

According to the above configuration, the sub sensor section is providedso as not to be positioned in a region (touched region) where a userperforms a touch operation. Therefore, on the sub sensor section, theuser would not perform a touch operation. Accordingly, although the subsensor section detects a noise reflected in the touch panel, the subsensor section does not detect a signal generated by a touch operation.This can reliably prevent the sub sensor section from detecting a touchoperation.

Namely, since the above configuration does not allow the sub sensorsection to detect a signal generated by a touch operation, an outputsignal supplied from the sub sensor section does not include the signalgenerated by the touch operation. This prevents a case where the signalvalue derived from the touch operation is reduced by the subtractingoperation performed by the subtracting section. Namely, a noisecomponent is removed without reducing the signal generated by the touchoperation and detected by the main sensor section. This makes itpossible to further enhance detection sensitivity for a touch operation.

Preferably, the touch panel system of any of the embodiments of thepresent invention is configured such that: the main sensor section andthe sub sensor section are provided so as to be adjacent to each other.

According to the above configuration, the main sensor section and thesub sensor section are arranged so that a distance therebetween isshortest. Namely, the main sensor section and the sub sensor section areprovided under substantially the same condition. Therefore, a value of anoise signal included in an output signal from the sub sensor sectioncan be regarded as being the same as that of a noise signal included inan output signal from the main sensor section. This can more reliablyremove, by the subtracting operation performed by the subtractingsection, a noise component reflected in the touch panel. This makes itpossible to further enhance detection sensitivity for a touch operation.

The touch panel system of any of the embodiments of the presentinvention may be configured such that: the main sensor section is madeof one main sensor.

According to the above configuration, the main sensor section is made ofa single main sensor. This can provide a touch panel system capable ofdetermining the presence or absence of a touch operation.

The touch panel system of any of the embodiments of the presentinvention may be configured such that: the main sensor section is madeof a plurality of main sensors arranged in a matrix.

According to the above configuration, the main sensor section is made ofa plurality of main sensors arranged in a matrix. This can provide atouch panel system capable of determining (i) the presence or absence ofa touch operation and (ii) a touched position.

Preferably, the touch panel system of any of the embodiments of thepresent invention is configured so as to include: drive lines providedso as to intersect the sense lines; a drive line driving circuit fordriving the drive lines in parallel; capacitances being formed betweenthe sense lines and the drive lines; and a decoding section for decodingvalues of differences between the capacitances in a direction in whicheach of the drive lines extends which differences are found by thesubtracting section as the differences in signal between the respectivepairs of the sense lines adjacent to each other, based on output signalsthat the subtracting section receives from the sense lines.

According to the above configuration, the touch panel is paralleldriven, and the decoding section decodes the difference values of thecapacitances which difference values are found by the subtractingsection. Consequently, signals of the capacitances are multiplied by acode length (i.e., multiplied by N). Therefore, signal strengths of thecapacitances are increased, regardless of the number of drive lines.Further, provided that necessary signal strengths are merely equal tothose of a conventional method, it is possible to reduce the number oftimes that the drive lines should be driven. This makes it possible toreduce electric power consumption.

The touch panel system of any of the embodiments of the presentinvention may be configured such that: the subtracting section includesa third analog-to-digital converting section for converting, intodigital signals, analog signals supplied from the sense lines to thesubtracting section; and the subtracting section uses, in order to findthe differences in signal between the respective pairs of the senselines adjacent to each other, the digital signals obtained by the thirdanalog-to-digital converting section.

According to the above configuration, it is possible to remove a noiseby (ii) converting, into digital signals, analog signals outputted bythe touch panel, and thereafter by (ii) performing subtractingoperations.

The touch panel system of any of the embodiments of the presentinvention may be configured such that: the subtracting section includesa fourth analog-to-digital converting section for converting, intodigital signals, analog signals supplied from the sense lines to thesubtracting section; and the fourth analog-to-digital converting sectionconverts, into digital signals, the differences in signal between therespective pairs of the sense lines adjacent to each other, thedifferences being found by the subtracting section with use of theanalog signals.

According to the above configuration, it is possible to remove a noiseby (i) performing subtracting operations on analog signals outputted bythe touch panel, without converting the analog signals into digitalsignals, and thereafter by (ii) converting the resulting signal into adigital signal.

The touch panel system of any of the embodiments of the presentinvention may be configured such that: the subtracting section includesa total differential amplifier for finding, with use of the analogsignals, the differences in signal between the respective pairs of thesense lines adjacent to each other.

According to the above configuration, it is possible to remove a noiseby (i) causing the total differential amplifier to perform subtractingoperations on analog signals without converting the analog signals intodigital signals which analog signals are outputted by the touch panel,and thereafter by (ii) converting the resulting signal into a digitalsignal.

The touch panel system of any of the embodiments of the presentinvention may be configured so as to include: a non-touch operationinformation storage section for storing a first distribution ofdifferences between the capacitances which differences are decoded bythe decoding section when no touch operation is performed; and acalibration section for subtracting (i) the first distribution stored inthe non-touch operation information storage section from (ii) a seconddistribution of differences between the capacitances which differencesare decoded by the decoding section when a touch operation is performed,so as to calibrate the second distribution.

According to the above configuration, the non-touch operationinformation storage section stores the first distribution of thedifferences between the capacitances which differences are decoded bythe decoding section when no touch operation is performed. Further, thecalibration section subtracts (i) the first distribution stored in thenon-touch operation information storage section from (ii) the seconddistribution of the differences between the capacitances whichdifferences are found when a touch operation is performed. Namely, thecalibration section performs the following calculation: (the seconddistribution of the differences between the capacitances whichdifferences are found when the touch operation is performed)−(the firstdistribution of the differences between the capacitances whichdifferences are found when no touch operation is performed). This cancancel an offset inherent in the touch panel.

Preferably, the touch panel system of any of the embodiments of thepresent invention is configured so as to include: a judging section fordetermining the presence or absence of a touch operation based on acomparison of (i) the differences in signal between the respective pairsof the sense lines adjacent to each other which differences are found bythe subtracting section and (ii) positive and negative threshold values.

According to the above configuration, the judging section determines thepresence or absence of a touch operation based on the differences insignal between the respective pairs the sense lines adjacent to eachother from which differences a noise signal has been removed. This makesit possible to accurately determine the presence or absence of the touchoperation.

Preferably, the touch panel system of any of the embodiments of thepresent invention is configured such that: the judging section creates,based on the comparison of (i) the differences in signal between therespective pairs of the sense lines adjacent to each other whichdifferences are found by the subtracting section and (ii) the positiveand negative threshold values, an increase and decrease table whichindicates, in ternary, a distribution of differences between signals ofthe sense lines, and the judging section converts the increase anddecrease table into a binary image, so as to extract touch informationtherefrom.

According to the above configuration, the differences in signal betweenthe respective pairs of the sense lines adjacent to each other fromwhich differences a noise signal has been removed are inputted to thejudging section. Based on the comparison of (i) the differences insignal between the respective pairs of the sense lines adjacent to eachother and (ii) the positive and negative threshold values stored in thejudging section, the judging section creates the increase and decreasetable indicating, in ternary, the distribution of the differences insignal between the respective pairs of the sense lines adjacent to eachother. Further, the judging section binarizes the increase and decreasetable, so that the increase and decrease table is converted into thebinary image. Consequently, from the binary image thus converted,candidates of a touched position are extracted. Thus, by recognizing thetouch information (the size, position, etc. of the touch) based on thebinary image, it is possible not only to determine the presence orabsence of the touch operation but also to recognize the touchinformation more accurately.

Preferably, the touch panel system of any of the embodiments of thepresent invention is configured to further include a display device, thetouch panel being provided to a front surface of the display device.

According to the above configuration, since the touch panel is providedon the front surface of the display device, it is possible to reliablyremove a noise generated in the display device.

Preferably, the touch panel system of any of the embodiments of thepresent invention is configured such that: the display device is aliquid crystal display, a plasma display, an organic electroluminescencedisplay, or a field emission display.

According to the above configuration, the display device is made of anyof various kinds of displays used in generally-used electronic devices.Therefore, it is possible to provide a touch panel system having a greatversatility.

A capacitive touch sensor panel of the present invention includes: aplurality of vertical electrodes (i) each including a repeat of firstbasic shapes connected to one another in a vertical direction, the firstbasic shapes each including a fine wire, (ii) provided on a verticalelectrode surface, and (iii) arranged at a predetermined interval in ahorizontal direction; a plurality of horizontal electrodes (i) eachincluding a repeat of second basic shapes connected to one another inthe horizontal direction, the second basic shapes each including a finewire, (ii) provided on a horizontal electrode surface parallel to thevertical electrode surface, and (iii) arranged at a predeterminedinterval in the vertical direction; and an insulator provided betweenthe vertical electrode surface and the horizontal electrode surface soas to insulate the plurality of vertical electrodes and the plurality ofhorizontal electrodes from each other, the plurality of verticalelectrodes and the plurality of horizontal electrodes (i) being disposedso that, as viewed in a direction perpendicular to the verticalelectrode surface, the plurality of vertical electrodes include nosegment coincident with the plurality of horizontal electrodes and (ii)forming a uniform grid having no gap.

The above arrangement disposes (I) a plurality of vertical electrodes(i) each including a repeat of first basic shapes connected to oneanother in a vertical direction, the first basic shapes each including afine wire, (ii) provided on a vertical electrode surface, and (iii)arranged at a predetermined interval in a horizontal direction and (II)a plurality of horizontal electrodes (i) each including a repeat ofsecond basic shapes connected to one another in the horizontaldirection, the second basic shapes each including a fine wire, (ii)provided on a horizontal electrode surface parallel to the verticalelectrode surface, and (iii) arranged at a predetermined interval in thevertical direction so that (i) as viewed in a direction perpendicular tothe vertical electrode surface, the plurality of vertical electrodesinclude no segment coincident with the plurality of horizontalelectrodes and that (ii) the plurality of vertical electrodes and theplurality of horizontal electrodes form a uniform grid having no gap.Thus, preparing an electrode distribution with (i) the verticalelectrodes, (ii) the horizontal electrodes, and (iii) an insulating filmsandwiched therebetween forms a uniform grid having no visible gap. Suchan electrode distribution, as placed on a display device, can preventmoire and the like from occurring.

A capacitive touch sensor system of the present invention includes: atouch sensor panel of the present invention.

An information input-output device of the present invention includes:the touch sensor system of the present invention.

A capacitive touch sensor panel of the present invention is arrangedsuch that a plurality of vertical electrodes and a plurality ofhorizontal electrodes are so disposed that (i) as viewed in thedirection perpendicular to the vertical electrode surface, the pluralityof vertical electrodes include no segment coincident with the pluralityof horizontal electrodes and that (ii) the plurality of verticalelectrodes and the plurality of horizontal electrodes form a uniformgrid having no gap. Thus, the capacitive touch sensor panel, as placedon a display device, can prevent moire and the like from occurring.

The capacitive touch sensor panel of the present embodiment maypreferably be arranged such that the fine wire included in the firstbasic shapes and the fine wire included in the second basic shapes eachextend in an oblique direction.

According to the above arrangement, the fine wire included in the firstbasic shapes and the fine wire included in the second basic shapes areeach inclined with respect to a black matrix of the display. The abovearrangement thus reduces the possibility of moire occurring.

The capacitive touch sensor panel of the present embodiment maypreferably be arranged such that the grid has a rectangular outline.

According to the above arrangement, the vertical electrodes and thehorizontal electrodes form a grid having a rectangular outline as viewedin the direction perpendicular to the vertical electrode surface. Theabove arrangement thus makes it possible to easily join, directly torespective portions corresponding to sides of the rectangular outline ofthe uniform grid having no gap, (i) address lines for driving thehorizontal electrodes or the vertical electrodes and (ii) address linesfor reading out signals from the vertical electrodes or the horizontalelectrodes.

The capacitive touch sensor panel of the present embodiment maypreferably be arranged such that the first basic shapes and the secondbasic shapes each have line symmetry with respect to a vertical centerline extending in the vertical direction.

With the above arrangement, the first basic shapes and the second basicshapes each have a symmetric shape. The above arrangement can thusimprove accuracy of reading coordinates on the basis of a change to acapacitance distribution which change is caused by a touch inputinvolving use of a pen.

The capacitive touch sensor panel of the present embodiment maypreferably be arranged such that the first basic shapes and the secondbasic shapes each have point symmetry.

With the above arrangement, the first basic shapes and the second basicshapes each have a symmetric shape. The above arrangement can thusimprove accuracy of reading coordinates on the basis of a change to acapacitance distribution which change is caused by a touch inputinvolving use of a pen.

The capacitive touch sensor panel of the present embodiment maypreferably be arranged such that the first basic shapes and the secondbasic shapes each have line symmetry with respect to (i) a verticalcenter line extending in the vertical direction and (ii) a horizontalcenter line extending in the horizontal direction.

With the above arrangement, the first basic shapes and the second basicshapes each have a symmetric shape. The above arrangement can thusimprove accuracy of reading coordinates on the basis of a change to acapacitance distribution which change is caused by a touch inputinvolving use of a pen.

The capacitive touch sensor panel of the present embodiment maypreferably be arranged such that the first basic shapes are eachinternally connected in the vertical direction at two or more fine-wirepoints; and the second basic shapes are each internally connected in thehorizontal direction at two or more fine-wire points.

With the above arrangement, adjacent ones of the first basic shapes areconnected to each other at two or more fine-wire points, while adjacentones of the second basic shapes are also connected to each other at twoor more fine-wire points. Thus, even if one fine wire is broken duringproduction, the remaining fine wire can prevent total disconnection.

The present invention is not limited to the description of theembodiments above, but may be altered by a skilled person within thescope of the claims. An embodiment based on a proper combination oftechnical means disclosed in different embodiments is encompassed in thetechnical scope of the present invention. Namely, the embodiments aboveare just examples in all respects, and provide no limitations. The scopeof the present invention is indicated by the claims, rather than by thedescriptions of the embodiments. Any meanings equivalent to the claimsand all modifications made in the scope of the claims are includedwithin the scope of the present invention.

INDUSTRIAL APPLICABILITY

The present invention is applicable to various kinds of electronicdevices including touch panels, for example, to televisions, personalcomputers, mobile phones, digital cameras, portable game devices,electronic photo frames, personal digital assistants, electronic books,home electronic appliances, ticket vending machines, automatic tellermachines, and car navigation systems.

The present invention is applicable to a capacitive touch sensor panelincluding (i) a plurality of vertical electrodes provided on a verticalelectrode surface and arranged at predetermined intervals in ahorizontal direction, (ii) a plurality of horizontal electrodes providedon a horizontal electrode surface, which is parallel to the verticalelectrode surface, and arranged at predetermined intervals in a verticaldirection, and (iii) an insulator provided between the verticalelectrode surface and the horizontal electrode surface to insulate thevertical electrodes from the horizontal electrodes. The presentinvention is further applicable to a capacitive touch sensor systemincluding the above capacitive touch sensor panel and to an informationinput-output device.

REFERENCE SIGNS LIST

-   -   1 Touch panel system    -   1 a Touch panel system    -   1 b Touch panel system    -   1 c Touch panel system    -   1 d Touch panel system    -   1 e Touch panel system    -   1 f Touch panel system    -   1 g Touch panel system    -   1 h Touch panel system    -   1 i Touch panel system    -   1 j Touch panel system    -   1 k Touch panel system    -   1 m Touch panel system    -   1 n Touch panel system    -   1 o Touch panel system    -   1 p Touch panel system (touch panel system, capacitive touch        sensor system)    -   2 Display device    -   3 Touch panel    -   3 a Touch panel    -   3 b Touch panel    -   3 c Touch panel    -   3 d Touch panel (capacitive touch sensor panel)    -   4 Touch panel controller    -   6 Vertical electrode    -   7 Horizontal electrode    -   8 Basic shape (first basic shape)    -   9 Basic shape (second basic shape)    -   10 Grid    -   12 Display    -   13, 14 Transparent adhesive    -   15 Cover film    -   16 Driver    -   17 Sense amplifier    -   18 Timing generator    -   19 AD converter    -   20 Capacitance distribution calculating section    -   21 Touch recognizing section    -   22 Capacitance value distribution detecting circuit    -   31 Main sensor (main sensor section)    -   31 a Main sensor group (main sensor section)    -   31 b Main sensor group (sensor section)    -   32 Sub sensor (sub sensor section)    -   32 a Sub sensor group (sub sensor section)    -   33 Sense line    -   34 Sub sense line    -   35 Drive line    -   41 Subtracting section    -   41 a Subtracting section    -   46 Adding section    -   47 Electric charge integrator (calculation section)    -   48 Analog-to-digital converting section (first analog-to-digital        converting section, second analog-to-digital converting section)    -   48 a Analog-to-digital converting section (third        analog-to-digital converting section, fourth analog-to-digital        converting section)    -   49 Differential amplifier    -   50 Total differential amplifier    -   58 Decoding section    -   59 Judging section    -   61 Non-touch operation information storage section    -   62 Calibration section    -   203 Substrate (insulator)    -   204 Surface (vertical electrode surface)    -   205 Surface (horizontal electrode surface)    -   250 Electronic blackboard (electronic device, information        input-output device)    -   C1 Vertical center line    -   C2 Horizontal center line    -   P Center point

The invention claimed is:
 1. A touch panel system comprising, a touchpanel; and a touch panel controller for processing a signal suppliedfrom the touch panel, the touch panel including a sensor section, thesensor section being provided with a plurality of sense lines anddetecting a touch operation performed with respect to the touch panel,the touch panel controller including a subtracting section for (i)receiving signals from the sensor section and (ii) finding differencesin signal between, among the sense lines, respective pairs of senselines adjacent to each other, the touch panel system further comprising:drive lines provided so as to intersect the sense lines; a drive linedriving circuit for driving the drive lines in parallel; andcapacitances being formed between the sense lines and the drive lines,the subtracting section receiving output signals from the sense lines,and finding differences between the capacitances on each of the drivelines in a direction in which the each of the drive lines extends, thedifferences being found as the differences in signal between therespective pairs of the sense lines adjacent to each other, the touchpanel system further comprising: a decoding section for decoding thevalues of the differences between the capacitances, which differencesare found by the subtracting section, the decoding being carried out insuch a manner that an inner product of each of code sequences fordriving the drive lines in parallel and each of difference outputsequences of the sense lines, which difference output sequencescorrespond to the code sequences, is calculated; and a switch forswitching a signal to be supplied to the subtracting section so that thesubtracting section finds a first difference which is expressed by(Sn+1)−Sn or a second difference which is expressed by Sn−(Sn−1), thefirst difference corresponding to a difference between (i) a signal of asense line Sn which is selected from the plurality of sense lines and(ii) a signal of a sense line Sn+1, which is one of two sense linesadjacent to the sense line Sn, the two sense lines being the sense lineSn+1 and a sense line Sn−1 each of which is included in the plurality ofsense lines, the second difference corresponding to a difference between(i) the signal of the sense line Sn and (ii) a signal of the sense lineSn−1, which is the other one of the two sense lines, the touch panelfurther comprising: a plurality of vertical electrodes (i) eachincluding a repeat of first basic shapes connected to one another in avertical direction, the first basic shapes each including a fine wire,(ii) provided on a vertical electrode surface, and (iii) arranged at apredetermined interval in a horizontal direction; a plurality ofhorizontal electrodes (i) each including a repeat of second basic shapesconnected to one another in the horizontal direction, the second basicshapes each including a fine wire, (ii) provided on a horizontalelectrode surface parallel to the vertical electrode surface, and (iii)arranged at a predetermined interval in the vertical direction; and aninsulator provided between the vertical electrode surface and thehorizontal electrode surface so as to insulate the plurality of verticalelectrodes and the plurality of horizontal electrodes from each other,the plurality of vertical electrodes and the plurality of horizontalelectrodes (i) being disposed so that, as viewed in a directionperpendicular to the vertical electrode surface, the plurality ofvertical electrodes include no segment coincident with the plurality ofhorizontal electrodes and (ii) forming a uniform grid having no gap. 2.The touch panel system as set forth in claim 1, wherein: the switchincludes two terminals, the switch being arranged such that one of thetwo terminals is selected; the code sequences for driving the drivelines in parallel are the following code sequences (a component is 1 or−1) for driving the first drive line through the Mth drive line inparallel, $\begin{matrix}{d_{1} = \left( {d_{11},d_{12},\ldots\mspace{11mu},d_{1N}} \right)} \\{d_{2} = \left( {d_{21},d_{22},\ldots\mspace{11mu},d_{2N}} \right)} \\\vdots \\{{d_{M} = \left( {d_{M\; 1},d_{M\; 2},\ldots\mspace{11mu},d_{MN}} \right)};}\end{matrix}$ difference output sequences “S_(j,P) (j=1, . . . , [L/2],P=1, 2) (L indicates the number of sense lines, [n]=an integer part ofn)” of the sense lines, which difference output sequences correspond tothe code sequences, are defined as follows, S_(j,1): an output sequencefor d₁ through d_(M) when the switches SW select one of the twoterminals S_(j,2): an output sequence for d₁ through d_(M) when theswitches SW select the other one of the two terminals; and the decodingsection calculates an inner product of each of the code sequences fordriving the drive lines in parallel and each of the difference outputsequences of the sense line, which difference output sequencescorrespond to the code sequences.
 3. The touch panel system as set forthin claim 2, wherein: the subtracting section includes a firstanalog-to-digital converting section for converting, into digitalsignals, analog signals supplied from the sense lines to the subtractingsection; and the subtracting section uses, in order to find thedifferences in signal between the respective pairs of the sense linesadjacent to each other, the digital signals obtained by the firstanalog-to-digital converting section.
 4. The touch panel system as setforth in claim 2, wherein: the subtracting section includes a firstanalog-to-digital converting section for converting, into digitalsignals, analog signals supplied from the sense lines to the subtractingsection; and the first analog-to-digital converting section converts,into digital signals, the differences in signal between the respectivepairs of the sense lines adjacent to each other, the differences beingfound by the subtracting section with use of the analog signals.
 5. Thetouch panel system as set forth in claim 4, wherein: the subtractingsection includes a total differential amplifier for finding, with use ofthe analog signals, the differences in signal between the respectivepairs of the sense lines adjacent to each other.
 6. The touch panelsystem as set forth in claim 4, further comprising: a judging sectionfor determining the presence or absence of a touch operation based on acomparison of (i) the differences in signal between the respective pairsof the sense lines adjacent to each other which differences are found bythe subtracting section and (ii) positive and negative threshold values.7. The touch panel system as set forth in claim 2, further comprising: anon-touch operation information storage section for storing a firstdistribution of differences between the capacitances which differencesare decoded by the decoding section when no touch operation isperformed; and a calibration section for subtracting (i) the firstdistribution stored in the non-touch operation information storagesection from (ii) a second distribution of differences between thecapacitances which differences are decoded by the decoding section whena touch operation is performed, so as to calibrate the seconddistribution.
 8. An electronic device comprising: a touch panel systemas set forth in claim
 2. 9. The touch panel system as set forth in claim1, wherein: the subtracting section includes a first analog-to-digitalfor converting, into digital signals, analog signals supplied from thesense lines to the subtracting section; and the first analog-to-digitalconverting section converts, into digital signals, the differences insignal between the respective pairs of the sense lines adjacent to eachother, the differences being found by the subtracting section with useof the analog signals.
 10. The touch panel system as set forth in claim9, wherein: the subtracting section includes a total differentialamplifier for finding, with use of the analog signals, the differencesin signal between the respective pairs of the sense lines adjacent toeach other.
 11. The touch panel system as set forth in claim 9, furthercomprising: a judging section for determining the presence or absence ofa touch operation based on a comparison of (i) the differences in signalbetween the respective pairs of the sense lines adjacent to each otherwhich differences are found by the subtracting section and (ii) positiveand negative threshold values.
 12. The touch panel system as set forthin claim 11, wherein: the judging section creates, based on thecomparison of (i) the differences in signal between the respective pairsof the sense lines adjacent to each other which differences are found bythe subtracting section and (ii) the positive and negative thresholdvalues, an increase and decrease table which indicates, in ternary, adistribution of differences between signals of the sense lines, aid thejudging section converts the increase and decrease table into a binaryimage, so as to extract touch information therefrom.
 13. The touch panelsystem as set forth in claim 1, further comprising: a non-touchoperation information storage section for storing a first distributionof differences between the capacitances which differences are decoded bythe decoding section when no touch operation is performed; and acalibration section for subtracting (i) the first distribution stored inthe non-touch operation information storage section from (ii) a seconddistribution of differences between the capacitances which differencesare decoded by the decoding section when a touch operation is performed,so as to calibrate the second distribution.
 14. The touch panel systemas set forth in claim 1, further comprising: a display device, the touchpanel being provided to a front surface of the display device.
 15. Thetouch panel system as set forth in claim 14, wherein: the display deviceis a liquid crystal display, a plasma display, an organicelectroluminescence display, or a field emission display.
 16. Anelectronic device comprising: a touch panel system as set forth inclaim
 1. 17. A touch panel system comprising, a touch panel; and a touchpanel controller for processing a signal supplied from the touch panel,the touch panel including a sensor section, the sensor section beingprovided with a plurality of sense lines and detecting a touch operationperformed with respect to the touch panel, the touch panel controllerincluding a subtracting section for (i) receiving signals from thesensor section and (ii) finding differences in signal between, among thesense lines, respective pairs of sense lines adjacent to each other, thetouch panel system further comprising: drive lines provided so as tointersect the sense lines; a drive line driving circuit for driving thedrive lines in parallel; and capacitances being formed between the senselines and the drive lines, the subtracting section receiving outputsignals from the sense lines, and finding differences between thecapacitances on each of the drive lines in a direction in which the eachof the drive lines extends, the differences being found as thedifferences m signal between the respective pairs of the sense linesadjacent to each other, the touch panel system further comprising: adecoding section for decoding the values of the differences between thecapacitances, which differences are found by the subtracting section,the decoding being carried out in such a manner that an inner product ofeach of code sequences for driving the drive lines in parallel and eachof difference output sequences of the sense lines, which differenceoutput sequences correspond to the code sequences, is calculated, thetouch panel further comprising: a plurality of vertical electrodes (i)each including a repeat of first basic shapes connected to one anotherin a vertical direction, the first basic shapes each including a finewire, (ii) provided on a vertical electrode surface, and (iii) arrangedat a predetermined interval in a horizontal direction; a plurality ofhorizontal electrodes (i) each including a repeat of second basic shapesconnected to one another in the horizontal direction, the second basicshapes each including a fine wire, (ii) provided on a horizontalelectrode surface parallel to the vertical electrode surface, and (iii)arranged at a predetermined interval in the vertical direction; and aninsulator provided between the vertical electrode surface and thehorizontal electrode surface so as to insulate the plurality of verticalelectrodes and the plurality of horizontal electrodes from each other,the plurality of vertical electrodes and the plurality of horizontalelectrodes (i) being disposed so that, as viewed in a directionperpendicular to the vertical electrode surface, the plurality ofvertical electrodes include no segment coincident with the plurality ofhorizontal electrodes and (ii) forming a uniform grid having no gap. 18.The touch panel system as set forth in claim 17, wherein: thesubtracting section finds a first difference which is expressed by(Sn+1)−Sn and a second difference which is expressed by Sn−(Sn−1), thefirst difference corresponding to a difference between (i) a signal of asense line Sn which is selected from the plurality of sense lines and(ii) a signal of a sense line Sn+1, which is one of two sense linesadjacent to the sense line Sn, the two sense lines being the sense lineSn+1 and a sense line Sn−1 each of which is included in the plurality ofsense lines, the second difference corresponding to a difference between(i) the signal of the sense line Sn and (ii) a signal of the sense lineSn−1, which is the other one of the two sense lines.
 19. The touch panelsystem as set forth in claim 17, wherein: the code sequences areorthogonal sequences or M sequences.